/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.7.8.  By combining all the individual C code files into this 
** single large file, the entire code can be compiled as a single translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other
................................................................................
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_INTTYPES_H
#include <inttypes.h>
#endif

/*
** The number of samples of an index that SQLite takes in order to 
** construct a histogram of the table content when running ANALYZE
** and with SQLITE_ENABLE_STAT2
*/
#define SQLITE_INDEX_SAMPLES 10

/*
** The following macros are used to cast pointers to integers and
** integers to pointers.  The way you do this varies from one compiler
** to the next, so we have developed the following set of #if statements
** to generate appropriate macros for a wide range of compilers.
**
** The correct "ANSI" way to do this is to use the intptr_t type. 
................................................................................
**
** On Windows, if the SQLITE_WIN32_MALLOC_VALIDATE macro is defined and the
** assert() macro is enabled, each call into the Win32 native heap subsystem
** will cause HeapValidate to be called.  If heap validation should fail, an
** assertion will be triggered.
**
** (Historical note:  There used to be several other options, but we've
** pared it down to just these two.)
**
** If none of the above are defined, then set SQLITE_SYSTEM_MALLOC as
** the default.
*/
#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_WIN32_MALLOC)+defined(SQLITE_MEMDEBUG)>1
# error "At most one of the following compile-time configuration options\
 is allows: SQLITE_SYSTEM_MALLOC, SQLITE_WIN32_MALLOC, SQLITE_MEMDEBUG"
................................................................................
** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.8"
#define SQLITE_VERSION_NUMBER 3007008
#define SQLITE_SOURCE_ID      "2011-09-17 17:29:20 b31a7d7db9040d8eedaf1ecd89ea0033f579d0f1"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode.  If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
** 




*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7
#define SQLITE_FCNTL_SYNC_OMITTED     8
#define SQLITE_FCNTL_WIN32_AV_RETRY   9
#define SQLITE_FCNTL_PERSIST_WAL     10


/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
................................................................................
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.
** The minimum allocation size is capped at 2^12. Reasonable values
** for the minimum allocation size are 2^5 through 2^8.</dd>
**
** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
................................................................................
** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes.

**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
................................................................................
** WHERE clause might influence the choice of query plan for a statement,
** then the statement will be automatically recompiled, as if there had been 
** a schema change, on the first  [sqlite3_step()] call following any change
** to the [sqlite3_bind_text | bindings] of that [parameter]. 
** ^The specific value of WHERE-clause [parameter] might influence the 
** choice of query plan if the parameter is the left-hand side of a [LIKE]
** or [GLOB] operator or if the parameter is compared to an indexed column
** and the [SQLITE_ENABLE_STAT2] compile-time option is enabled.
** the 
** </li>
** </ol>
*/
SQLITE_API int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
................................................................................
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.







**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called
** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
** ^If the fifth argument is
................................................................................
**
** ^The sqlite3_data_count(P) interface returns the number of columns in the
** current row of the result set of [prepared statement] P.
** ^If prepared statement P does not have results ready to return
** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
** interfaces) then sqlite3_data_count(P) returns 0.
** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.






**
** See also: [sqlite3_column_count()]
*/
SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes
................................................................................
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.





** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not
................................................................................
**
** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
** <dd>This parameter returns the approximate number of of bytes of heap
** and lookaside memory used by all prepared statements associated with
** the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
** </dd>












** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
#define SQLITE_DBSTATUS_CACHE_USED           1
#define SQLITE_DBSTATUS_SCHEMA_USED          2
#define SQLITE_DBSTATUS_STMT_USED            3
#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6


#define SQLITE_DBSTATUS_MAX                  6   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS counters] that measure the number
................................................................................
**
** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
** <dd>^This is the number of rows inserted into transient indices that
** were created automatically in order to help joins run faster.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance by adding permanent indices that do not
** need to be reinitialized each time the statement is run.</dd>
**
** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2
#define SQLITE_STMTSTATUS_AUTOINDEX         3

/*
................................................................................
** SQLITE_MAX_U32 is a u64 constant that is the maximum u64 value
** that can be stored in a u32 without loss of data.  The value
** is 0x00000000ffffffff.  But because of quirks of some compilers, we
** have to specify the value in the less intuitive manner shown:
*/
#define SQLITE_MAX_U32  ((((u64)1)<<32)-1)













/*
** Macros to determine whether the machine is big or little endian,
** evaluated at runtime.
*/
#ifdef SQLITE_AMALGAMATION
SQLITE_PRIVATE const int sqlite3one = 1;
#else
................................................................................
** Allowed values for the flags parameter to sqlite3PagerOpen().
**
** NOTE: These values must match the corresponding BTREE_ values in btree.h.
*/
#define PAGER_OMIT_JOURNAL  0x0001    /* Do not use a rollback journal */
#define PAGER_NO_READLOCK   0x0002    /* Omit readlocks on readonly files */
#define PAGER_MEMORY        0x0004    /* In-memory database */
#define PAGER_SORTER        0x0020    /* Accumulator in external merge sort */

/*
** Valid values for the second argument to sqlite3PagerLockingMode().
*/
#define PAGER_LOCKINGMODE_QUERY      -1
#define PAGER_LOCKINGMODE_NORMAL      0
#define PAGER_LOCKINGMODE_EXCLUSIVE   1
................................................................................
SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager*);
SQLITE_PRIVATE const sqlite3_vfs *sqlite3PagerVfs(Pager*);
SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
SQLITE_PRIVATE int sqlite3PagerNosync(Pager*);
SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);



/* Functions used to truncate the database file. */
SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager*,Pgno);

#if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL)
SQLITE_PRIVATE void *sqlite3PagerCodec(DbPage *);
#endif
................................................................................

#ifdef SQLITE_MUTEX_OMIT
/*
** If this is a no-op implementation, implement everything as macros.
*/
#define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)
#define sqlite3_mutex_free(X)
#define sqlite3_mutex_enter(X)
#define sqlite3_mutex_try(X)      SQLITE_OK
#define sqlite3_mutex_leave(X)
#define sqlite3_mutex_held(X)     ((void)(X),1)
#define sqlite3_mutex_notheld(X)  ((void)(X),1)
#define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)
#define sqlite3MutexInit()        SQLITE_OK
#define sqlite3MutexEnd()



#endif /* defined(SQLITE_MUTEX_OMIT) */

/************** End of mutex.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/


/*
................................................................................
struct Table {
  char *zName;         /* Name of the table or view */
  int iPKey;           /* If not negative, use aCol[iPKey] as the primary key */
  int nCol;            /* Number of columns in this table */
  Column *aCol;        /* Information about each column */
  Index *pIndex;       /* List of SQL indexes on this table. */
  int tnum;            /* Root BTree node for this table (see note above) */
  unsigned nRowEst;    /* Estimated rows in table - from sqlite_stat1 table */
  Select *pSelect;     /* NULL for tables.  Points to definition if a view. */
  u16 nRef;            /* Number of pointers to this Table */
  u8 tabFlags;         /* Mask of TF_* values */
  u8 keyConf;          /* What to do in case of uniqueness conflict on iPKey */
  FKey *pFKey;         /* Linked list of all foreign keys in this table */
  char *zColAff;       /* String defining the affinity of each column */
#ifndef SQLITE_OMIT_CHECK
................................................................................
** algorithm to employ whenever an attempt is made to insert a non-unique
** element.
*/
struct Index {
  char *zName;     /* Name of this index */
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
  u8 bUnordered;   /* Use this index for == or IN queries only */
  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */



  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */

};

/*
** Each sample stored in the sqlite_stat2 table is represented in memory 
** using a structure of this type.

*/
struct IndexSample {
  union {
    char *z;        /* Value if eType is SQLITE_TEXT or SQLITE_BLOB */
    double r;       /* Value if eType is SQLITE_FLOAT or SQLITE_INTEGER */

  } u;
  u8 eType;         /* SQLITE_NULL, SQLITE_INTEGER ... etc. */
  u8 nByte;         /* Size in byte of text or blob. */



};

/*
** Each token coming out of the lexer is an instance of
** this structure.  Tokens are also used as part of an expression.
**
** Note if Token.z==0 then Token.dyn and Token.n are undefined and
................................................................................
** and the WhereInfo.wctrlFlags member.
*/
#define WHERE_ORDERBY_NORMAL   0x0000 /* No-op */
#define WHERE_ORDERBY_MIN      0x0001 /* ORDER BY processing for min() func */
#define WHERE_ORDERBY_MAX      0x0002 /* ORDER BY processing for max() func */
#define WHERE_ONEPASS_DESIRED  0x0004 /* Want to do one-pass UPDATE/DELETE */
#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
#define WHERE_OMIT_OPEN        0x0010 /* Table cursors are already open */
#define WHERE_OMIT_CLOSE       0x0020 /* Omit close of table & index cursors */
#define WHERE_FORCE_TABLE      0x0040 /* Do not use an index-only search */
#define WHERE_ONETABLE_ONLY    0x0080 /* Only code the 1st table in pTabList */


/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second
** half does the tail of the WHERE loop.  An instance of
** this structure is returned by the first half and passed
** into the second half to give some continuity.
................................................................................
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
SQLITE_PRIVATE   int sqlite3ViewGetColumnNames(Parse*,Table*);
#else
# define sqlite3ViewGetColumnNames(A,B) 0
#endif

SQLITE_PRIVATE void sqlite3DropTable(Parse*, SrcList*, int, int);

SQLITE_PRIVATE void sqlite3DeleteTable(sqlite3*, Table*);
#ifndef SQLITE_OMIT_AUTOINCREMENT
SQLITE_PRIVATE   void sqlite3AutoincrementBegin(Parse *pParse);
SQLITE_PRIVATE   void sqlite3AutoincrementEnd(Parse *pParse);
#else
# define sqlite3AutoincrementBegin(X)
# define sqlite3AutoincrementEnd(X)
................................................................................
SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8, 
                        void(*)(void*));
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *, const void*, int, u8);
#ifdef SQLITE_ENABLE_STAT2
SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *, u8, char *, int, int *);
#endif
SQLITE_PRIVATE int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);
SQLITE_PRIVATE void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
#ifndef SQLITE_AMALGAMATION
SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[];
SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[];
................................................................................
#  define sqlite3VtabRollback(X)
#  define sqlite3VtabCommit(X)
#  define sqlite3VtabInSync(db) 0
#  define sqlite3VtabLock(X) 
#  define sqlite3VtabUnlock(X)
#  define sqlite3VtabUnlockList(X)
#  define sqlite3VtabSavepoint(X, Y, Z) SQLITE_OK

#else
SQLITE_PRIVATE    void sqlite3VtabClear(sqlite3 *db, Table*);
SQLITE_PRIVATE    int sqlite3VtabSync(sqlite3 *db, char **);
SQLITE_PRIVATE    int sqlite3VtabRollback(sqlite3 *db);
SQLITE_PRIVATE    int sqlite3VtabCommit(sqlite3 *db);
SQLITE_PRIVATE    void sqlite3VtabLock(VTable *);
SQLITE_PRIVATE    void sqlite3VtabUnlock(VTable *);
SQLITE_PRIVATE    void sqlite3VtabUnlockList(sqlite3*);
SQLITE_PRIVATE    int sqlite3VtabSavepoint(sqlite3 *, int, int);

#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
#endif
SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);
SQLITE_PRIVATE void sqlite3VtabArgExtend(Parse*, Token*);
................................................................................
SQLITE_PRIVATE void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3*, Table*);
SQLITE_PRIVATE const char *sqlite3JournalModename(int);
SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
SQLITE_PRIVATE int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);

/* Declarations for functions in fkey.c. All of these are replaced by
** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
** key functionality is available. If OMIT_TRIGGER is defined but
................................................................................
*/
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config = {
   SQLITE_DEFAULT_MEMSTATUS,  /* bMemstat */
   1,                         /* bCoreMutex */
   SQLITE_THREADSAFE==1,      /* bFullMutex */
   SQLITE_USE_URI,            /* bOpenUri */
   0x7ffffffe,                /* mxStrlen */
   100,                       /* szLookaside */
   500,                       /* nLookaside */
   {0,0,0,0,0,0,0,0},         /* m */
   {0,0,0,0,0,0,0,0,0},       /* mutex */
   {0,0,0,0,0,0,0,0,0,0,0},   /* pcache */
   (void*)0,                  /* pHeap */
   0,                         /* nHeap */
   0, 0,                      /* mnHeap, mxHeap */
................................................................................
#endif
#ifdef SQLITE_ENABLE_OVERSIZE_CELL_CHECK
  "ENABLE_OVERSIZE_CELL_CHECK",
#endif
#ifdef SQLITE_ENABLE_RTREE
  "ENABLE_RTREE",
#endif
#ifdef SQLITE_ENABLE_STAT2
  "ENABLE_STAT2",
#endif
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
  "ENABLE_UNLOCK_NOTIFY",
#endif
#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
  "ENABLE_UPDATE_DELETE_LIMIT",
#endif
................................................................................
#endif
#ifdef SQLITE_OMIT_WSD
  "OMIT_WSD",
#endif
#ifdef SQLITE_OMIT_XFER_OPT
  "OMIT_XFER_OPT",
#endif
#ifdef SQLITE_PAGECACHE_BLOCKALLOC
  "PAGECACHE_BLOCKALLOC",
#endif
#ifdef SQLITE_PERFORMANCE_TRACE
  "PERFORMANCE_TRACE",
#endif
#ifdef SQLITE_PROXY_DEBUG
  "PROXY_DEBUG",
#endif
#ifdef SQLITE_SECURE_DELETE
................................................................................
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);


#ifdef SQLITE_OMIT_MERGE_SORT
# define sqlite3VdbeSorterInit(Y,Z)      SQLITE_OK
# define sqlite3VdbeSorterWrite(X,Y,Z)   SQLITE_OK
# define sqlite3VdbeSorterClose(Y,Z)
# define sqlite3VdbeSorterRowkey(Y,Z)    SQLITE_OK
# define sqlite3VdbeSorterRewind(X,Y,Z)  SQLITE_OK
................................................................................
      db->pnBytesFreed = 0;

      *pHighwater = 0;
      *pCurrent = nByte;

      break;
    }























    default: {
      rc = SQLITE_ERROR;
    }
  }
  sqlite3_mutex_leave(db->mutex);
  return rc;
................................................................................
  if( p->validTZ ){
    computeJD(p);
  }
  return 0;
}

/*
** Set the time to the current time reported by the VFS


*/
static void setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
  sqlite3 *db = sqlite3_context_db_handle(context);
  sqlite3OsCurrentTimeInt64(db->pVfs, &p->iJD);
  p->validJD = 1;




}

/*
** Attempt to parse the given string into a Julian Day Number.  Return
** the number of errors.
**
** The following are acceptable forms for the input string:
................................................................................
){
  double r;
  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    setDateTimeToCurrent(context, p);
    return 0;
  }else if( sqlite3AtoF(zDate, &r, sqlite3Strlen30(zDate), SQLITE_UTF8) ){
    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
    p->validJD = 1;
    return 0;
  }
  return 1;
}
................................................................................
  DateTime *p
){
  int i;
  const unsigned char *z;
  int eType;
  memset(p, 0, sizeof(*p));
  if( argc==0 ){
    setDateTimeToCurrent(context, p);

  }else if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
                   || eType==SQLITE_INTEGER ){
    p->iJD = (sqlite3_int64)(sqlite3_value_double(argv[0])*86400000.0 + 0.5);
    p->validJD = 1;
  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
................................................................................
  int argc,
  sqlite3_value **argv
){
  time_t t;
  char *zFormat = (char *)sqlite3_user_data(context);
  sqlite3 *db;
  sqlite3_int64 iT;


  char zBuf[20];

  UNUSED_PARAMETER(argc);
  UNUSED_PARAMETER(argv);

  db = sqlite3_context_db_handle(context);
  sqlite3OsCurrentTimeInt64(db->pVfs, &iT);
  t = iT/1000 - 10000*(sqlite3_int64)21086676;
#ifdef HAVE_GMTIME_R
  {
    struct tm sNow;
    gmtime_r(&t, &sNow);
    strftime(zBuf, 20, zFormat, &sNow);
  }
#else
  {
    struct tm *pTm;
    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
    pTm = gmtime(&t);
    strftime(zBuf, 20, zFormat, pTm);

    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
  }
#endif



  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);

}
#endif

/*
** This function registered all of the above C functions as SQL
** functions.  This should be the only routine in this file with
** external linkage.
................................................................................

/*
** Register a VFS with the system.  It is harmless to register the same
** VFS multiple times.  The new VFS becomes the default if makeDflt is
** true.
*/
SQLITE_API int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
  sqlite3_mutex *mutex = 0;
#ifndef SQLITE_OMIT_AUTOINIT
  int rc = sqlite3_initialize();
  if( rc ) return rc;
#endif
  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(mutex);
  vfsUnlink(pVfs);
  if( makeDflt || vfsList==0 ){
    pVfs->pNext = vfsList;
    vfsList = pVfs;
  }else{
    pVfs->pNext = vfsList->pNext;
................................................................................
** the public domain.  The original comments are included here for
** completeness.  They are very out-of-date but might be useful as
** an historical reference.  Most of the "enhancements" have been backed
** out so that the functionality is now the same as standard printf().
**
**************************************************************************
**
** The following modules is an enhanced replacement for the "printf" subroutines
** found in the standard C library.  The following enhancements are
** supported:
**
**      +  Additional functions.  The standard set of "printf" functions
**         includes printf, fprintf, sprintf, vprintf, vfprintf, and
**         vsprintf.  This module adds the following:
**
**           *  snprintf -- Works like sprintf, but has an extra argument
**                          which is the size of the buffer written to.
**
**           *  mprintf --  Similar to sprintf.  Writes output to memory
**                          obtained from malloc.
**
**           *  xprintf --  Calls a function to dispose of output.
**
**           *  nprintf --  No output, but returns the number of characters
**                          that would have been output by printf.
**
**           *  A v- version (ex: vsnprintf) of every function is also
**              supplied.
**
**      +  A few extensions to the formatting notation are supported:
**
**           *  The "=" flag (similar to "-") causes the output to be
**              be centered in the appropriately sized field.
**
**           *  The %b field outputs an integer in binary notation.
**
**           *  The %c field now accepts a precision.  The character output
**              is repeated by the number of times the precision specifies.
**
**           *  The %' field works like %c, but takes as its character the
**              next character of the format string, instead of the next
**              argument.  For example,  printf("%.78'-")  prints 78 minus
**              signs, the same as  printf("%.78c",'-').
**
**      +  When compiled using GCC on a SPARC, this version of printf is
**         faster than the library printf for SUN OS 4.1.
**
**      +  All functions are fully reentrant.
**
*/

/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
................................................................................
  if( N>0 ){
    sqlite3StrAccumAppend(pAccum, zSpaces, N);
  }
}

/*
** On machines with a small stack size, you can redefine the
** SQLITE_PRINT_BUF_SIZE to be less than 350.
*/
#ifndef SQLITE_PRINT_BUF_SIZE
# if defined(SQLITE_SMALL_STACK)
#   define SQLITE_PRINT_BUF_SIZE 50
# else
#   define SQLITE_PRINT_BUF_SIZE 350
# endif
#endif
#define etBUFSIZE SQLITE_PRINT_BUF_SIZE  /* Size of the output buffer */

/*
** The root program.  All variations call this core.
**
** INPUTS:
**   func   This is a pointer to a function taking three arguments
**            1. A pointer to anything.  Same as the "arg" parameter.
**            2. A pointer to the list of characters to be output
**               (Note, this list is NOT null terminated.)
**            3. An integer number of characters to be output.
**               (Note: This number might be zero.)
**
**   arg    This is the pointer to anything which will be passed as the
**          first argument to "func".  Use it for whatever you like.
**
**   fmt    This is the format string, as in the usual print.
**
**   ap     This is a pointer to a list of arguments.  Same as in
**          vfprint.
**
** OUTPUTS:
**          The return value is the total number of characters sent to
**          the function "func".  Returns -1 on a error.
**
** Note that the order in which automatic variables are declared below
** seems to make a big difference in determining how fast this beast
** will run.

*/
SQLITE_PRIVATE void sqlite3VXPrintf(
  StrAccum *pAccum,                  /* Accumulate results here */
  int useExtended,                   /* Allow extended %-conversions */
  const char *fmt,                   /* Format string */
  va_list ap                         /* arguments */
){
................................................................................
  etByte flag_blanksign;     /* True if " " flag is present */
  etByte flag_alternateform; /* True if "#" flag is present */
  etByte flag_altform2;      /* True if "!" flag is present */
  etByte flag_zeropad;       /* True if field width constant starts with zero */
  etByte flag_long;          /* True if "l" flag is present */
  etByte flag_longlong;      /* True if the "ll" flag is present */
  etByte done;               /* Loop termination flag */


  sqlite_uint64 longvalue;   /* Value for integer types */
  LONGDOUBLE_TYPE realvalue; /* Value for real types */
  const et_info *infop;      /* Pointer to the appropriate info structure */
  char buf[etBUFSIZE];       /* Conversion buffer */
  char prefix;               /* Prefix character.  "+" or "-" or " " or '\0'. */
  etByte xtype = 0;          /* Conversion paradigm */
  char *zExtra;              /* Extra memory used for etTCLESCAPE conversions */
#ifndef SQLITE_OMIT_FLOATING_POINT
  int  exp, e2;              /* exponent of real numbers */

  double rounder;            /* Used for rounding floating point values */
  etByte flag_dp;            /* True if decimal point should be shown */
  etByte flag_rtz;           /* True if trailing zeros should be removed */
  etByte flag_exp;           /* True to force display of the exponent */
  int nsd;                   /* Number of significant digits returned */
#endif


  length = 0;
  bufpt = 0;
  for(; (c=(*fmt))!=0; ++fmt){
    if( c!='%' ){
      int amt;
      bufpt = (char *)fmt;
      amt = 1;
      while( (c=(*++fmt))!='%' && c!=0 ) amt++;
................................................................................
      c = *++fmt;
    }else{
      while( c>='0' && c<='9' ){
        width = width*10 + c - '0';
        c = *++fmt;
      }
    }
    if( width > etBUFSIZE-10 ){
      width = etBUFSIZE-10;
    }
    /* Get the precision */
    if( c=='.' ){
      precision = 0;
      c = *++fmt;
      if( c=='*' ){
        precision = va_arg(ap,int);
        if( precision<0 ) precision = -precision;
................................................................................
          return;
        }
        break;
      }
    }
    zExtra = 0;


    /* Limit the precision to prevent overflowing buf[] during conversion */
    if( precision>etBUFSIZE-40 && (infop->flags & FLAG_STRING)==0 ){
      precision = etBUFSIZE-40;
    }

    /*
    ** At this point, variables are initialized as follows:
    **
    **   flag_alternateform          TRUE if a '#' is present.
    **   flag_altform2               TRUE if a '!' is present.
    **   flag_plussign               TRUE if a '+' is present.
    **   flag_leftjustify            TRUE if a '-' is present or if the
................................................................................
          }
          prefix = 0;
        }
        if( longvalue==0 ) flag_alternateform = 0;
        if( flag_zeropad && precision<width-(prefix!=0) ){
          precision = width-(prefix!=0);
        }

        bufpt = &buf[etBUFSIZE-1];










        if( xtype==etORDINAL ){
          static const char zOrd[] = "thstndrd";
          int x = (int)(longvalue % 10);
          if( x>=4 || (longvalue/10)%10==1 ){
            x = 0;
          }
          buf[etBUFSIZE-3] = zOrd[x*2];
          buf[etBUFSIZE-2] = zOrd[x*2+1];
          bufpt -= 2;
        }
        {
          register const char *cset;      /* Use registers for speed */
          register int base;
          cset = &aDigits[infop->charset];
          base = infop->base;
          do{                                           /* Convert to ascii */
            *(--bufpt) = cset[longvalue%base];
            longvalue = longvalue/base;
          }while( longvalue>0 );
        }
        length = (int)(&buf[etBUFSIZE-1]-bufpt);
        for(idx=precision-length; idx>0; idx--){
          *(--bufpt) = '0';                             /* Zero pad */
        }
        if( prefix ) *(--bufpt) = prefix;               /* Add sign */
        if( flag_alternateform && infop->prefix ){      /* Add "0" or "0x" */
          const char *pre;
          char x;
          pre = &aPrefix[infop->prefix];
          for(; (x=(*pre))!=0; pre++) *(--bufpt) = x;
        }
        length = (int)(&buf[etBUFSIZE-1]-bufpt);
        break;
      case etFLOAT:
      case etEXP:
      case etGENERIC:
        realvalue = va_arg(ap,double);
#ifdef SQLITE_OMIT_FLOATING_POINT
        length = 0;
#else
        if( precision<0 ) precision = 6;         /* Set default precision */
        if( precision>etBUFSIZE/2-10 ) precision = etBUFSIZE/2-10;
        if( realvalue<0.0 ){
          realvalue = -realvalue;
          prefix = '-';
        }else{
          if( flag_plussign )          prefix = '+';
          else if( flag_blanksign )    prefix = ' ';
          else                         prefix = 0;
................................................................................
          }
        }
        bufpt = buf;
        /*
        ** If the field type is etGENERIC, then convert to either etEXP
        ** or etFLOAT, as appropriate.
        */
        flag_exp = xtype==etEXP;
        if( xtype!=etFLOAT ){
          realvalue += rounder;
          if( realvalue>=10.0 ){ realvalue *= 0.1; exp++; }
        }
        if( xtype==etGENERIC ){
          flag_rtz = !flag_alternateform;
          if( exp<-4 || exp>precision ){
................................................................................
          flag_rtz = 0;
        }
        if( xtype==etEXP ){
          e2 = 0;
        }else{
          e2 = exp;
        }








        nsd = 0;
        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
        /* The sign in front of the number */
        if( prefix ){
          *(bufpt++) = prefix;
        }
        /* Digits prior to the decimal point */
................................................................................
        /* Significant digits after the decimal point */
        while( (precision--)>0 ){
          *(bufpt++) = et_getdigit(&realvalue,&nsd);
        }
        /* Remove trailing zeros and the "." if no digits follow the "." */
        if( flag_rtz && flag_dp ){
          while( bufpt[-1]=='0' ) *(--bufpt) = 0;
          assert( bufpt>buf );
          if( bufpt[-1]=='.' ){
            if( flag_altform2 ){
              *(bufpt++) = '0';
            }else{
              *(--bufpt) = 0;
            }
          }
        }
        /* Add the "eNNN" suffix */
        if( flag_exp || xtype==etEXP ){
          *(bufpt++) = aDigits[infop->charset];
          if( exp<0 ){
            *(bufpt++) = '-'; exp = -exp;
          }else{
            *(bufpt++) = '+';
          }
          if( exp>=100 ){
................................................................................
          *(bufpt++) = (char)(exp%10+'0');             /* 1's digit */
        }
        *bufpt = 0;

        /* The converted number is in buf[] and zero terminated. Output it.
        ** Note that the number is in the usual order, not reversed as with
        ** integer conversions. */
        length = (int)(bufpt-buf);
        bufpt = buf;

        /* Special case:  Add leading zeros if the flag_zeropad flag is
        ** set and we are not left justified */
        if( flag_zeropad && !flag_leftjustify && length < width){
          int i;
          int nPad = width - length;
          for(i=width; i>=nPad; i--){
................................................................................
    if( flag_leftjustify ){
      register int nspace;
      nspace = width-length;
      if( nspace>0 ){
        appendSpace(pAccum, nspace);
      }
    }
    if( zExtra ){
      sqlite3_free(zExtra);
    }
  }/* End for loop over the format string */
} /* End of function */

/*
** Append N bytes of text from z to the StrAccum object.
*/
SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
  assert( z!=0 || N==0 );
  if( p->tooBig | p->mallocFailed ){
    testcase(p->tooBig);
    testcase(p->mallocFailed);
    return;
  }

  if( N<0 ){
    N = sqlite3Strlen30(z);
  }
  if( N==0 || NEVER(z==0) ){
    return;
  }
  if( p->nChar+N >= p->nAlloc ){
................................................................................
      }
      if( p->useMalloc==1 ){
        zNew = sqlite3DbRealloc(p->db, zOld, p->nAlloc);
      }else{
        zNew = sqlite3_realloc(zOld, p->nAlloc);
      }
      if( zNew ){
        if( zOld==0 ) memcpy(zNew, p->zText, p->nChar);
        p->zText = zNew;
      }else{
        p->mallocFailed = 1;
        sqlite3StrAccumReset(p);
        return;
      }
    }
  }

  memcpy(&p->zText[p->nChar], z, N);
  p->nChar += N;
}

/*
** Finish off a string by making sure it is zero-terminated.
** Return a pointer to the resulting string.  Return a NULL
................................................................................
** is set to the length of the returned string in bytes. The call should
** arrange to call sqlite3DbFree() on the returned pointer when it is
** no longer required.
** 
** If a malloc failure occurs, NULL is returned and the db.mallocFailed
** flag set.
*/
#ifdef SQLITE_ENABLE_STAT2
SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *db, u8 enc, char *z, int n, int *pnOut){
  Mem m;
  memset(&m, 0, sizeof(m));
  m.db = db;
  sqlite3VdbeMemSetStr(&m, z, n, SQLITE_UTF8, SQLITE_STATIC);
  if( sqlite3VdbeMemTranslate(&m, enc) ){
    assert( db->mallocFailed );
................................................................................
      esign = -1;
      z+=incr;
    }else if( *z=='+' ){
      z+=incr;
    }
    /* copy digits to exponent */
    while( z<zEnd && sqlite3Isdigit(*z) ){
      e = e*10 + (*z - '0');
      z+=incr;
      eValid = 1;
    }
  }

  /* skip trailing spaces */
  if( nDigits && eValid ){
................................................................................
        if( esign<0 ){
          result = s / scale;
          result /= 1.0e+308;
        }else{
          result = s * scale;
          result *= 1.0e+308;
        }






      }else{
        /* 1.0e+22 is the largest power of 10 than can be 
        ** represented exactly. */
        while( e%22 ) { scale *= 1.0e+1; e -= 1; }
        while( e>0 ) { scale *= 1.0e+22; e -= 22; }
        if( esign<0 ){
          result = s / scale;
................................................................................
#ifdef SQLITE_DEBUG
static int unixMutexHeld(void) {
  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
#endif


#ifdef SQLITE_DEBUG
/*
** Helper function for printing out trace information from debugging
** binaries. This returns the string represetation of the supplied
** integer lock-type.
*/
static const char *azFileLock(int eFileLock){
  switch( eFileLock ){
................................................................................
  ** The reason a single byte cannot be used instead of the 'shared byte
  ** range' is that some versions of windows do not support read-locks. By
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode = pFile->pInode;
  struct flock lock;
  int tErrno = 0;

  assert( pFile );
  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
      azFileLock(eFileLock), azFileLock(pFile->eFileLock),
      azFileLock(pInode->eFileLock), pInode->nShared , getpid()));

  /* If there is already a lock of this type or more restrictive on the
  ** unixFile, do nothing. Don't use the end_lock: exit path, as
  ** unixEnterMutex() hasn't been called yet.
  */
  if( pFile->eFileLock>=eFileLock ){
    OSTRACE(("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
................................................................................
** remove the write lock on a region when a read lock is set.
*/
static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int rc = SQLITE_OK;
  int h;

  assert( pFile );
  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
      pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
      getpid()));

  assert( eFileLock<=SHARED_LOCK );
  if( pFile->eFileLock<=eFileLock ){
    return SQLITE_OK;
  }
  unixEnterMutex();
  h = pFile->h;
  pInode = pFile->pInode;
  assert( pInode->nShared!=0 );
  if( pFile->eFileLock>SHARED_LOCK ){
    assert( pInode->eFileLock==pFile->eFileLock );
    SimulateIOErrorBenign(1);
    SimulateIOError( h=(-1) )
    SimulateIOErrorBenign(0);

#ifndef NDEBUG
    /* When reducing a lock such that other processes can start
    ** reading the database file again, make sure that the
    ** transaction counter was updated if any part of the database
    ** file changed.  If the transaction counter is not updated,
    ** other connections to the same file might not realize that
    ** the file has changed and hence might not know to flush their
    ** cache.  The use of a stale cache can lead to database corruption.
    */
#if 0
    assert( pFile->inNormalWrite==0
         || pFile->dbUpdate==0
         || pFile->transCntrChng==1 );
#endif
    pFile->inNormalWrite = 0;
#endif

    /* downgrading to a shared lock on NFS involves clearing the write lock
    ** before establishing the readlock - to avoid a race condition we downgrade
    ** the lock in 2 blocks, so that part of the range will be covered by a 
    ** write lock until the rest is covered by a read lock:
................................................................................
    ** the lock.
    */
    pInode->nShared--;
    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( unixFileLock(pFile, &lock)==0 ){
        pInode->eFileLock = NO_LOCK;
      }else{
        rc = SQLITE_IOERR_UNLOCK;
	pFile->lastErrno = errno;
        pInode->eFileLock = NO_LOCK;
        pFile->eFileLock = NO_LOCK;
................................................................................
    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
    if( pShmNode->mutex==0 ){
      rc = SQLITE_NOMEM;
      goto shm_open_err;
    }

    if( pInode->bProcessLock==0 ){
      pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
                               (sStat.st_mode & 0777));
      if( pShmNode->h<0 ){
        const char *zRO;

        zRO = sqlite3_uri_parameter(pDbFd->zPath, "readonly_shm");
        if( zRO && sqlite3GetBoolean(zRO) ){
          pShmNode->h = robust_open(zShmFilename, O_RDONLY,
                                    (sStat.st_mode & 0777));

          pShmNode->isReadonly = 1;
        }


        if( pShmNode->h<0 ){
          rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
          goto shm_open_err;
        }
      }
  
      /* Check to see if another process is holding the dead-man switch.
................................................................................
  */
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
  assert( zFilename==0 || zFilename[0]=='/' 
    || pVfs->pAppData==(void*)&autolockIoFinder );
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif




  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->zPath = zFilename;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
    pNew->ctrlFlags = UNIXFILE_EXCL;
  }else{
................................................................................

  else if( pLockingStyle == &dotlockIoMethods ){
    /* Dotfile locking uses the file path so it needs to be included in
    ** the dotlockLockingContext 
    */
    char *zLockFile;
    int nFilename;

    nFilename = (int)strlen(zFilename) + 6;
    zLockFile = (char *)sqlite3_malloc(nFilename);
    if( zLockFile==0 ){
      rc = SQLITE_NOMEM;
    }else{
      sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
    }
................................................................................
    ** the following naming conventions:
    **
    **   "<path to db>-journal"
    **   "<path to db>-wal"
    **   "<path to db>-journalNN"
    **   "<path to db>-walNN"
    **
    ** where NN is a 4 digit decimal number. The NN naming schemes are 
    ** used by the test_multiplex.c module.
    */
    nDb = sqlite3Strlen30(zPath) - 1; 




    while( nDb>0 && zPath[nDb]!='-' ) nDb--;
    if( nDb==0 ) return SQLITE_OK;





    memcpy(zDb, zPath, nDb);
    zDb[nDb] = '\0';

    if( 0==osStat(zDb, &sStat) ){
      *pMode = sStat.st_mode & 0777;
    }else{
      rc = SQLITE_IOERR_FSTAT;
................................................................................
/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**

** On success, return 0.  Return 1 if the time and date cannot be found.
*/
static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){
  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;

#if defined(NO_GETTOD)
  time_t t;
  time(&t);
  *piNow = ((sqlite3_int64)t)*1000 + unixEpoch;
#elif OS_VXWORKS
  struct timespec sNow;
  clock_gettime(CLOCK_REALTIME, &sNow);
  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_nsec/1000000;
#else
  struct timeval sNow;
  gettimeofday(&sNow, 0);
  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_usec/1000;



#endif

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
  }
#endif
  UNUSED_PARAMETER(NotUsed);
  return 0;
}

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
  sqlite3_int64 i;

  UNUSED_PARAMETER(NotUsed);
  unixCurrentTimeInt64(0, &i);
  *prNow = i/86400000.0;
  return 0;
}

/*
** We added the xGetLastError() method with the intention of providing
** better low-level error messages when operating-system problems come up
** during SQLite operation.  But so far, none of that has been implemented
** in the core.  So this routine is never called.  For now, it is merely
................................................................................
           h, zName, dwDesiredAccess, 
           h==INVALID_HANDLE_VALUE ? "failed" : "ok"));

  if( h==INVALID_HANDLE_VALUE ){
    pFile->lastErrno = GetLastError();
    winLogError(SQLITE_CANTOPEN, "winOpen", zUtf8Name);
    free(zConverted);
    if( isReadWrite ){
      return winOpen(pVfs, zName, id, 
             ((flags|SQLITE_OPEN_READONLY)&~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)), pOutFlags);
    }else{
      return SQLITE_CANTOPEN_BKPT;
    }
  }

................................................................................
  free(zConverted);
  return (void*)h;
}
static void winDlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
  UNUSED_PARAMETER(pVfs);
  getLastErrorMsg(nBuf, zBufOut);
}
void (*winDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol))(void){
  UNUSED_PARAMETER(pVfs);
#if SQLITE_OS_WINCE
  /* The GetProcAddressA() routine is only available on wince. */
  return (void(*)(void))GetProcAddressA((HANDLE)pHandle, zSymbol);
#else
  /* All other windows platforms expect GetProcAddress() to take
  ** an Ansi string regardless of the _UNICODE setting */
  return (void(*)(void))GetProcAddress((HANDLE)pHandle, zSymbol);
#endif
}
void winDlClose(sqlite3_vfs *pVfs, void *pHandle){
  UNUSED_PARAMETER(pVfs);
  FreeLibrary((HANDLE)pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define winDlOpen  0
  #define winDlError 0
  #define winDlSym   0
................................................................................
/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**

** On success, return 0.  Return 1 if the time and date cannot be found.
*/
static int winCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
  /* FILETIME structure is a 64-bit value representing the number of 
     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5). 
  */
  FILETIME ft;
  static const sqlite3_int64 winFiletimeEpoch = 23058135*(sqlite3_int64)8640000;
................................................................................
      (sqlite3_int64)2000000000 + (sqlite3_int64)2000000000 + (sqlite3_int64)294967296;

#if SQLITE_OS_WINCE
  SYSTEMTIME time;
  GetSystemTime(&time);
  /* if SystemTimeToFileTime() fails, it returns zero. */
  if (!SystemTimeToFileTime(&time,&ft)){
    return 1;
  }
#else
  GetSystemTimeAsFileTime( &ft );
#endif

  *piNow = winFiletimeEpoch +
            ((((sqlite3_int64)ft.dwHighDateTime)*max32BitValue) + 
................................................................................

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
  }
#endif
  UNUSED_PARAMETER(pVfs);
  return 0;
}

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int winCurrentTime(sqlite3_vfs *pVfs, double *prNow){
  int rc;
  sqlite3_int64 i;
  rc = winCurrentTimeInt64(pVfs, &i);
  if( !rc ){
    *prNow = i/86400000.0;
  }
  return rc;
................................................................................


typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;
typedef struct PGroup PGroup;

typedef struct PGroupBlock PGroupBlock;
typedef struct PGroupBlockList PGroupBlockList;

/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
** of one or more PCaches that are able to recycle each others unpinned
** pages when they are under memory pressure.  A PGroup is an instance of
** the following object.
**
** This page cache implementation works in one of two modes:
................................................................................
struct PGroup {
  sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
  int nMaxPage;                  /* Sum of nMax for purgeable caches */
  int nMinPage;                  /* Sum of nMin for purgeable caches */
  int mxPinned;                  /* nMaxpage + 10 - nMinPage */
  int nCurrentPage;              /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;   /* LRU list of unpinned pages */
#ifdef SQLITE_PAGECACHE_BLOCKALLOC
  int isBusy;                    /* Do not run ReleaseMemory() if true */
  PGroupBlockList *pBlockList;   /* List of block-lists for this group */
#endif
};

/*
** If SQLITE_PAGECACHE_BLOCKALLOC is defined when the library is built,
** each PGroup structure has a linked list of the the following starting
** at PGroup.pBlockList. There is one entry for each distinct page-size 
** currently used by members of the PGroup (i.e. 1024 bytes, 4096 bytes
** etc.). Variable PGroupBlockList.nByte is set to the actual allocation
** size requested by each pcache, which is the database page-size plus
** the various header structures used by the pcache, pager and btree layers.
** Usually around (pgsz+200) bytes.
**
** This size (pgsz+200) bytes is not allocated efficiently by some
** implementations of malloc. In particular, some implementations are only
** able to allocate blocks of memory chunks of 2^N bytes, where N is some
** integer value. Since the page-size is a power of 2, this means we
** end up wasting (pgsz-200) bytes in each allocation.
**
** If SQLITE_PAGECACHE_BLOCKALLOC is defined, the (pgsz+200) byte blocks
** are not allocated directly. Instead, blocks of roughly M*(pgsz+200) bytes 
** are requested from malloc allocator. After a block is returned,
** sqlite3MallocSize() is used to determine how many (pgsz+200) byte
** allocations can fit in the space returned by malloc(). This value may
** be more than M.
**
** The blocks are stored in a doubly-linked list. Variable PGroupBlock.nEntry
** contains the number of allocations that will fit in the aData[] space.
** nEntry is limited to the number of bits in bitmask mUsed. If a slot
** within aData is in use, the corresponding bit in mUsed is set. Thus
** when (mUsed+1==(1 << nEntry)) the block is completely full.
**
** Each time a slot within a block is freed, the block is moved to the start
** of the linked-list. And if a block becomes completely full, then it is
** moved to the end of the list. As a result, when searching for a free
** slot, only the first block in the list need be examined. If it is full,
** then it is guaranteed that all blocks are full.
*/
struct PGroupBlockList {
  int nByte;                     /* Size of each allocation in bytes */
  PGroupBlock *pFirst;           /* First PGroupBlock in list */
  PGroupBlock *pLast;            /* Last PGroupBlock in list */
  PGroupBlockList *pNext;        /* Next block-list attached to group */
};

struct PGroupBlock {
  Bitmask mUsed;                 /* Mask of used slots */
  int nEntry;                    /* Maximum number of allocations in aData[] */
  u8 *aData;                     /* Pointer to data block */
  PGroupBlock *pNext;            /* Next PGroupBlock in list */
  PGroupBlock *pPrev;            /* Previous PGroupBlock in list */
  PGroupBlockList *pList;        /* Owner list */
};

/* Minimum value for PGroupBlock.nEntry */
#define PAGECACHE_BLOCKALLOC_MINENTRY 15

/* Each page cache is an instance of the following object.  Every
** open database file (including each in-memory database and each
** temporary or transient database) has a single page cache which
** is an instance of this object.
**
** Pointers to structures of this type are cast and returned as 
** opaque sqlite3_pcache* handles.
................................................................................
** a pointer to a block of szPage bytes of data and the return value is
** a pointer to the associated PgHdr1 structure.
**
**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X );
*/
#define PGHDR1_TO_PAGE(p)    (void*)(((char*)p) - p->pCache->szPage)
#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage)

/*
** Blocks used by the SQLITE_PAGECACHE_BLOCKALLOC blocks to store/retrieve 
** a PGroupBlock pointer based on a pointer to a page buffer. 
*/
#define PAGE_SET_BLOCKPTR(pCache, pPg, pBlock) \
  ( *(PGroupBlock **)&(((u8*)pPg)[sizeof(PgHdr1) + pCache->szPage]) = pBlock )

#define PAGE_GET_BLOCKPTR(pCache, pPg) \
  ( *(PGroupBlock **)&(((u8*)pPg)[sizeof(PgHdr1) + pCache->szPage]) )


/*
** Macros to enter and leave the PCache LRU mutex.
*/
#define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
#define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)

................................................................................
    iSize = sqlite3MallocSize(p);
    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
    return iSize;
  }
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */

#ifdef SQLITE_PAGECACHE_BLOCKALLOC
/*
** The block pBlock belongs to list pList but is not currently linked in.
** Insert it into the start of the list.
*/
static void addBlockToList(PGroupBlockList *pList, PGroupBlock *pBlock){
  pBlock->pPrev = 0;
  pBlock->pNext = pList->pFirst;
  pList->pFirst = pBlock;
  if( pBlock->pNext ){
    pBlock->pNext->pPrev = pBlock;
  }else{
    assert( pList->pLast==0 );
    pList->pLast = pBlock;
  }
}

/*
** If there are no blocks in the list headed by pList, remove pList
** from the pGroup->pBlockList list and free it with sqlite3_free().
*/
static void freeListIfEmpty(PGroup *pGroup, PGroupBlockList *pList){
  assert( sqlite3_mutex_held(pGroup->mutex) );
  if( pList->pFirst==0 ){
    PGroupBlockList **pp;
    for(pp=&pGroup->pBlockList; *pp!=pList; pp=&(*pp)->pNext);
    *pp = (*pp)->pNext;
    sqlite3_free(pList);
  }
}
#endif /* SQLITE_PAGECACHE_BLOCKALLOC */

/*
** Allocate a new page object initially associated with cache pCache.
*/
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  int nByte = sizeof(PgHdr1) + pCache->szPage;
  void *pPg = 0;
  PgHdr1 *p;


#ifdef SQLITE_PAGECACHE_BLOCKALLOC
  PGroup *pGroup = pCache->pGroup;
  PGroupBlockList *pList;
  PGroupBlock *pBlock;
  int i;

  nByte += sizeof(PGroupBlockList *);
  nByte = ROUND8(nByte);

  for(pList=pGroup->pBlockList; pList; pList=pList->pNext){
    if( pList->nByte==nByte ) break;
  }
  if( pList==0 ){
    PGroupBlockList *pNew;
    assert( pGroup->isBusy==0 );
    assert( sqlite3_mutex_held(pGroup->mutex) );
    pGroup->isBusy = 1;  /* Disable sqlite3PcacheReleaseMemory() */
    pNew = (PGroupBlockList *)sqlite3MallocZero(sizeof(PGroupBlockList));
    pGroup->isBusy = 0;  /* Reenable sqlite3PcacheReleaseMemory() */
    if( pNew==0 ){
      /* malloc() failure. Return early. */
      return 0;
    }
#ifdef SQLITE_DEBUG
    for(pList=pGroup->pBlockList; pList; pList=pList->pNext){
      assert( pList->nByte!=nByte );
    }
#endif
    pNew->nByte = nByte;
    pNew->pNext = pGroup->pBlockList;
    pGroup->pBlockList = pNew;
    pList = pNew;
  }

  pBlock = pList->pFirst;
  if( pBlock==0 || pBlock->mUsed==(((Bitmask)1<<pBlock->nEntry)-1) ){
    int sz;

    /* Allocate a new block. Try to allocate enough space for the PGroupBlock
    ** structure and MINENTRY allocations of nByte bytes each. If the 
    ** allocator returns more memory than requested, then more than MINENTRY 
    ** allocations may fit in it. */
    assert( sqlite3_mutex_held(pGroup->mutex) );
    pcache1LeaveMutex(pCache->pGroup);
    sz = sizeof(PGroupBlock) + PAGECACHE_BLOCKALLOC_MINENTRY * nByte;
    pBlock = (PGroupBlock *)sqlite3Malloc(sz);
    pcache1EnterMutex(pCache->pGroup);

    if( !pBlock ){
      freeListIfEmpty(pGroup, pList);
      return 0;
    }
    pBlock->nEntry = (sqlite3MallocSize(pBlock) - sizeof(PGroupBlock)) / nByte;
    if( pBlock->nEntry>=BMS ){
      pBlock->nEntry = BMS-1;
    }
    pBlock->pList = pList;
    pBlock->mUsed = 0;
    pBlock->aData = (u8 *)&pBlock[1];
    addBlockToList(pList, pBlock);

    sz = sqlite3MallocSize(pBlock);
    sqlite3_mutex_enter(pcache1.mutex);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
    sqlite3_mutex_leave(pcache1.mutex);
  }

  for(i=0; pPg==0 && ALWAYS(i<pBlock->nEntry); i++){
    if( 0==(pBlock->mUsed & ((Bitmask)1<<i)) ){
      pBlock->mUsed |= ((Bitmask)1<<i);
      pPg = (void *)&pBlock->aData[pList->nByte * i];
    }
  }
  assert( pPg );
  PAGE_SET_BLOCKPTR(pCache, pPg, pBlock);

  /* If the block is now full, shift it to the end of the list */
  if( pBlock->mUsed==(((Bitmask)1<<pBlock->nEntry)-1) && pList->pLast!=pBlock ){
    assert( pList->pFirst==pBlock );
    assert( pBlock->pPrev==0 );
    assert( pList->pLast->pNext==0 );
    pList->pFirst = pBlock->pNext;
    pList->pFirst->pPrev = 0;
    pBlock->pPrev = pList->pLast;
    pBlock->pNext = 0;
    pList->pLast->pNext = pBlock;
    pList->pLast = pBlock;
  }
  p = PAGE_TO_PGHDR1(pCache, pPg);
  if( pCache->bPurgeable ){
    pCache->pGroup->nCurrentPage++;
  }
#else
  /* The group mutex must be released before pcache1Alloc() is called. This
  ** is because it may call sqlite3_release_memory(), which assumes that 
  ** this mutex is not held. */
  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  pcache1LeaveMutex(pCache->pGroup);
  pPg = pcache1Alloc(nByte);
  pcache1EnterMutex(pCache->pGroup);

  if( pPg ){
    p = PAGE_TO_PGHDR1(pCache, pPg);
    if( pCache->bPurgeable ){
      pCache->pGroup->nCurrentPage++;
    }
  }else{
    p = 0;
  }
#endif
  return p;
}

/*
** Free a page object allocated by pcache1AllocPage().
**
** The pointer is allowed to be NULL, which is prudent.  But it turns out
** that the current implementation happens to never call this routine
** with a NULL pointer, so we mark the NULL test with ALWAYS().
*/
static void pcache1FreePage(PgHdr1 *p){
  if( ALWAYS(p) ){
    PCache1 *pCache = p->pCache;
    void *pPg = PGHDR1_TO_PAGE(p);

#ifdef SQLITE_PAGECACHE_BLOCKALLOC
    PGroupBlock *pBlock = PAGE_GET_BLOCKPTR(pCache, pPg);
    PGroupBlockList *pList = pBlock->pList;
    int i = ((u8 *)pPg - pBlock->aData) / pList->nByte;

    assert( pPg==(void *)&pBlock->aData[i*pList->nByte] );
    assert( pBlock->mUsed & ((Bitmask)1<<i) );
    pBlock->mUsed &= ~((Bitmask)1<<i);

    /* Remove the block from the list. If it is completely empty, free it.
    ** Or if it is not completely empty, re-insert it at the start of the
    ** list. */
    if( pList->pFirst==pBlock ){
      pList->pFirst = pBlock->pNext;
      if( pList->pFirst ) pList->pFirst->pPrev = 0;
    }else{
      pBlock->pPrev->pNext = pBlock->pNext;
    }
    if( pList->pLast==pBlock ){
      pList->pLast = pBlock->pPrev;
      if( pList->pLast ) pList->pLast->pNext = 0;
    }else{
      pBlock->pNext->pPrev = pBlock->pPrev;
    }

    if( pBlock->mUsed==0 ){
      PGroup *pGroup = p->pCache->pGroup;

      int sz = sqlite3MallocSize(pBlock);
      sqlite3_mutex_enter(pcache1.mutex);
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -sz);
      sqlite3_mutex_leave(pcache1.mutex);
      freeListIfEmpty(pGroup, pList);
      sqlite3_free(pBlock);
    }else{
      addBlockToList(pList, pBlock);
    }
#else
    assert( sqlite3_mutex_held(p->pCache->pGroup->mutex) );
    pcache1Free(pPg);
#endif
    if( pCache->bPurgeable ){
      pCache->pGroup->nCurrentPage--;
    }
  }
}

/*
................................................................................
**
** nReq is the number of bytes of memory required. Once this much has
** been released, the function returns. The return value is the total number 
** of bytes of memory released.
*/
SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int nReq){
  int nFree = 0;
#ifdef SQLITE_PAGECACHE_BLOCKALLOC
  if( pcache1.grp.isBusy ) return 0;
#endif
  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
  assert( sqlite3_mutex_notheld(pcache1.mutex) );
  if( pcache1.pStart==0 ){
    PgHdr1 *p;
    pcache1EnterMutex(&pcache1.grp);
    while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){
      nFree += pcache1MemSize(PGHDR1_TO_PAGE(p));
................................................................................
  u8 noSync;                  /* Do not sync the journal if true */
  u8 fullSync;                /* Do extra syncs of the journal for robustness */
  u8 ckptSyncFlags;           /* SYNC_NORMAL or SYNC_FULL for checkpoint */
  u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
  u8 tempFile;                /* zFilename is a temporary file */
  u8 readOnly;                /* True for a read-only database */
  u8 memDb;                   /* True to inhibit all file I/O */
  u8 hasSeenStress;           /* pagerStress() called one or more times */

  /**************************************************************************
  ** The following block contains those class members that change during
  ** routine opertion.  Class members not in this block are either fixed
  ** when the pager is first created or else only change when there is a
  ** significant mode change (such as changing the page_size, locking_mode,
  ** or the journal_mode).  From another view, these class members describe
................................................................................
  int pageSize;               /* Number of bytes in a page */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  i64 journalSizeLimit;       /* Size limit for persistent journal files */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  int (*xBusyHandler)(void*); /* Function to call when busy */
  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */

#ifdef SQLITE_TEST
  int nHit, nMiss;            /* Cache hits and missing */
  int nRead, nWrite;          /* Database pages read/written */
#endif
  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
#ifdef SQLITE_HAS_CODEC
  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
  void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
  void (*xCodecFree)(void*);             /* Destructor for the codec */
................................................................................
      if( needPagerReset ){
        pager_reset(pPager);
        needPagerReset = 0;
      }
      rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){
          rc = SQLITE_OK;
          pPager->journalOff = szJ;
          break;
        }else if( rc==SQLITE_IOERR_SHORT_READ ){
          /* If the journal has been truncated, simply stop reading and
          ** processing the journal. This might happen if the journal was
          ** not completely written and synced prior to a crash.  In that
          ** case, the database should have never been written in the
................................................................................
){
  int rc;                         /* Return code */
#if defined(SQLITE_DEBUG) || defined(SQLITE_CHECK_PAGES)
  PgHdr *p;                       /* For looping over pages */
#endif

  assert( pPager->pWal );

#ifdef SQLITE_DEBUG
  /* Verify that the page list is in accending order */
  for(p=pList; p && p->pDirty; p=p->pDirty){
    assert( p->pgno < p->pDirty->pgno );
  }
#endif

................................................................................
  ** pages belonging to the same sector.
  **
  ** The doNotSpill flag inhibits all cache spilling regardless of whether
  ** or not a sync is required.  This is set during a rollback.
  **
  ** Spilling is also prohibited when in an error state since that could
  ** lead to database corruption.   In the current implementaton it 
  ** is impossible for sqlite3PCacheFetch() to be called with createFlag==1
  ** while in the error state, hence it is impossible for this routine to
  ** be called in the error state.  Nevertheless, we include a NEVER()
  ** test for the error state as a safeguard against future changes.
  */
  pPager->hasSeenStress = 1;
  if( NEVER(pPager->errCode) ) return SQLITE_OK;
  if( pPager->doNotSpill ) return SQLITE_OK;
  if( pPager->doNotSyncSpill && (pPg->flags & PGHDR_NEED_SYNC)!=0 ){
    return SQLITE_OK;
  }

  pPg->pDirty = 0;
................................................................................
  assert( (*ppPage)->pgno==pgno );
  assert( (*ppPage)->pPager==pPager || (*ppPage)->pPager==0 );

  if( (*ppPage)->pPager && !noContent ){
    /* In this case the pcache already contains an initialized copy of
    ** the page. Return without further ado.  */
    assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
    PAGER_INCR(pPager->nHit);
    return SQLITE_OK;

  }else{
    /* The pager cache has created a new page. Its content needs to 
    ** be initialized.  */

    PAGER_INCR(pPager->nMiss);
    pPg = *ppPage;
    pPg->pPager = pPager;

    /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
    ** number greater than this, or the unused locking-page, is requested. */
    if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
      rc = SQLITE_CORRUPT_BKPT;
................................................................................
        testcase( rc==SQLITE_NOMEM );
        sqlite3EndBenignMalloc();
      }
      memset(pPg->pData, 0, pPager->pageSize);
      IOTRACE(("ZERO %p %d\n", pPager, pgno));
    }else{
      assert( pPg->pPager==pPager );

      rc = readDbPage(pPg);
      if( rc!=SQLITE_OK ){
        goto pager_acquire_err;
      }
    }
    pager_set_pagehash(pPg);
  }
................................................................................
  a[7] = pPager->nMiss;
  a[8] = 0;  /* Used to be pPager->nOvfl */
  a[9] = pPager->nRead;
  a[10] = pPager->nWrite;
  return a;
}
#endif


























/*
** Return true if this is an in-memory pager.
*/
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager *pPager){
  return MEMDB;
}
................................................................................
      rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
                           pPager->pageSize, (u8*)pPager->pTmpSpace);
      pPager->pWal = 0;
    }
  }
  return rc;
}








#ifdef SQLITE_HAS_CODEC
/*
** This function is called by the wal module when writing page content
** into the log file.
**
** This function returns a pointer to a buffer containing the encrypted
................................................................................
  /* If iRead is non-zero, then it is the log frame number that contains the
  ** required page. Read and return data from the log file.
  */
  if( iRead ){
    int sz;
    i64 iOffset;
    sz = pWal->hdr.szPage;
    sz = (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
    testcase( sz<=32768 );
    testcase( sz>=65536 );
    iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
    *pInWal = 1;
    /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
    return sqlite3OsRead(pWal->pWalFd, pOut, nOut, iOffset);
  }
................................................................................
  ** If this Btree is a candidate for shared cache, try to find an
  ** existing BtShared object that we can share with
  */
  if( isMemdb==0 && isTempDb==0 ){
    if( vfsFlags & SQLITE_OPEN_SHAREDCACHE ){
      int nFullPathname = pVfs->mxPathname+1;
      char *zFullPathname = sqlite3Malloc(nFullPathname);
      sqlite3_mutex *mutexShared;
      p->sharable = 1;
      if( !zFullPathname ){
        sqlite3_free(p);
        return SQLITE_NOMEM;
      }
      sqlite3OsFullPathname(pVfs, zFilename, nFullPathname, zFullPathname);

      mutexOpen = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_OPEN);
      sqlite3_mutex_enter(mutexOpen);
      mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
      sqlite3_mutex_enter(mutexShared);

      for(pBt=GLOBAL(BtShared*,sqlite3SharedCacheList); pBt; pBt=pBt->pNext){
        assert( pBt->nRef>0 );
        if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager))
                 && sqlite3PagerVfs(pBt->pPager)==pVfs ){
          int iDb;
          for(iDb=db->nDb-1; iDb>=0; iDb--){
            Btree *pExisting = db->aDb[iDb].pBt;
................................................................................
    pBt->usableSize = pBt->pageSize - nReserve;
    assert( (pBt->pageSize & 7)==0 );  /* 8-byte alignment of pageSize */
   
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
    /* Add the new BtShared object to the linked list sharable BtShareds.
    */
    if( p->sharable ){
      sqlite3_mutex *mutexShared;
      pBt->nRef = 1;
      mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
      if( SQLITE_THREADSAFE && sqlite3GlobalConfig.bCoreMutex ){
        pBt->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_FAST);
        if( pBt->mutex==0 ){
          rc = SQLITE_NOMEM;
          db->mallocFailed = 0;
          goto btree_open_out;
        }
................................................................................
** Decrement the BtShared.nRef counter.  When it reaches zero,
** remove the BtShared structure from the sharing list.  Return
** true if the BtShared.nRef counter reaches zero and return
** false if it is still positive.
*/
static int removeFromSharingList(BtShared *pBt){
#ifndef SQLITE_OMIT_SHARED_CACHE
  sqlite3_mutex *pMaster;
  BtShared *pList;
  int removed = 0;

  assert( sqlite3_mutex_notheld(pBt->mutex) );
  pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(pMaster);
  pBt->nRef--;
  if( pBt->nRef<=0 ){
    if( GLOBAL(BtShared*,sqlite3SharedCacheList)==pBt ){
      GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt->pNext;
    }else{
      pList = GLOBAL(BtShared*,sqlite3SharedCacheList);
................................................................................
#endif
          rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
        offset -= ovflSize;
      }else{
        /* Need to read this page properly. It contains some of the
        ** range of data that is being read (eOp==0) or written (eOp!=0).
        */
        DbPage *pDbPage;


        int a = amt;


































        rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage);
        if( rc==SQLITE_OK ){
          aPayload = sqlite3PagerGetData(pDbPage);
          nextPage = get4byte(aPayload);
          if( a + offset > ovflSize ){
            a = ovflSize - offset;
          }
          rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
          sqlite3PagerUnref(pDbPage);
          offset = 0;


          amt -= a;
          pBuf += a;
        }
      }
    }
  }

  if( rc==SQLITE_OK && amt>0 ){
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
          c = sqlite3VdbeRecordCompare(nCell, pCellKey, pIdxKey);
          sqlite3_free(pCellKey);
        }
      }
      if( c==0 ){
        if( pPage->intKey && !pPage->leaf ){
          lwr = idx;
          upr = lwr - 1;
          break;
        }else{
          *pRes = 0;
          rc = SQLITE_OK;
          goto moveto_finish;
        }
      }
................................................................................
        upr = idx-1;
      }
      if( lwr>upr ){
        break;
      }
      pCur->aiIdx[pCur->iPage] = (u16)(idx = (lwr+upr)/2);
    }
    assert( lwr==upr+1 );
    assert( pPage->isInit );
    if( pPage->leaf ){
      chldPg = 0;
    }else if( lwr>=pPage->nCell ){
      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    }else{
      chldPg = get4byte(findCell(pPage, lwr));
................................................................................
      }else{
        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }



      k = get4byte(&pTrunk->aData[4]); /* # of leaves on this trunk page */
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
................................................................................
      /* Drop the cell from the parent page. apDiv[i] still points to
      ** the cell within the parent, even though it has been dropped.
      ** This is safe because dropping a cell only overwrites the first
      ** four bytes of it, and this function does not need the first
      ** four bytes of the divider cell. So the pointer is safe to use
      ** later on.  
      **
      ** Unless SQLite is compiled in secure-delete mode. In this case,
      ** the dropCell() routine will overwrite the entire cell with zeroes.
      ** In this case, temporarily copy the cell into the aOvflSpace[]
      ** buffer. It will be copied out again as soon as the aSpace[] buffer
      ** is allocated.  */
      if( pBt->secureDelete ){


        int iOff = SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent->aData);
        if( (iOff+szNew[i])>(int)pBt->usableSize ){
          rc = SQLITE_CORRUPT_BKPT;
          memset(apOld, 0, (i+1)*sizeof(MemPage*));
          goto balance_cleanup;
        }else{
          memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
          apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
................................................................................
    k = 0;                             /* Current 'new' sibling page */
    for(i=0; i<nCell; i++){
      int isDivider = 0;
      while( i==iNextOld ){
        /* Cell i is the cell immediately following the last cell on old
        ** sibling page j. If the siblings are not leaf pages of an
        ** intkey b-tree, then cell i was a divider cell. */

        pOld = apCopy[++j];
        iNextOld = i + !leafData + pOld->nCell + pOld->nOverflow;
        if( pOld->nOverflow ){
          nOverflow = pOld->nOverflow;
          iOverflow = i + !leafData + pOld->aOvfl[0].idx;
        }
        isDivider = !leafData;  
................................................................................
}

/*
** Release all resources associated with an sqlite3_backup* handle.
*/
SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p){
  sqlite3_backup **pp;                 /* Ptr to head of pagers backup list */
  sqlite3_mutex *mutex;                /* Mutex to protect source database */
  int rc;                              /* Value to return */

  /* Enter the mutexes */
  if( p==0 ) return SQLITE_OK;
  sqlite3_mutex_enter(p->pSrcDb->mutex);
  sqlite3BtreeEnter(p->pSrc);
  mutex = p->pSrcDb->mutex;
  if( p->pDestDb ){
    sqlite3_mutex_enter(p->pDestDb->mutex);
  }

  /* Detach this backup from the source pager. */
  if( p->pDestDb ){
    p->pSrc->nBackup--;
................................................................................
**
** The size of file pTo may be reduced by this operation. If anything 
** goes wrong, the transaction on pTo is rolled back. If successful, the 
** transaction is committed before returning.
*/
SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
  int rc;

  sqlite3_backup b;
  sqlite3BtreeEnter(pTo);
  sqlite3BtreeEnter(pFrom);








  /* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
  ** to 0. This is used by the implementations of sqlite3_backup_step()
  ** and sqlite3_backup_finish() to detect that they are being called
  ** from this function, not directly by the user.
  */
  memset(&b, 0, sizeof(b));
................................................................................
  ** or an error code.
  */
  sqlite3_backup_step(&b, 0x7FFFFFFF);
  assert( b.rc!=SQLITE_OK );
  rc = sqlite3_backup_finish(&b);
  if( rc==SQLITE_OK ){
    pTo->pBt->pageSizeFixed = 0;


  }


  sqlite3BtreeLeave(pFrom);
  sqlite3BtreeLeave(pTo);
  return rc;
}
#endif /* SQLITE_OMIT_VACUUM */

/************** End of backup.c **********************************************/
................................................................................

  if( !pExpr ){
    *ppVal = 0;
    return SQLITE_OK;
  }
  op = pExpr->op;

  /* op can only be TK_REGISTER if we have compiled with SQLITE_ENABLE_STAT2.
  ** The ifdef here is to enable us to achieve 100% branch test coverage even
  ** when SQLITE_ENABLE_STAT2 is omitted.
  */
#ifdef SQLITE_ENABLE_STAT2
  if( op==TK_REGISTER ) op = pExpr->op2;
#else
  if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
#endif

  /* Handle negative integers in a single step.  This is needed in the
  ** case when the value is -9223372036854775808.
................................................................................
}

/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){
  assert( addr>=0 );
  sqlite3VdbeChangeP2(p, addr, p->nOp);
}


/*
** If the input FuncDef structure is ephemeral, then free it.  If
** the FuncDef is not ephermal, then do nothing.
*/
................................................................................
#ifndef NDEBUG
/*
** Change the comment on the the most recently coded instruction.  Or
** insert a No-op and add the comment to that new instruction.  This
** makes the code easier to read during debugging.  None of this happens
** in a production build.
*/
SQLITE_PRIVATE void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
  va_list ap;
  if( !p ) return;
  assert( p->nOp>0 || p->aOp==0 );
  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
  if( p->nOp ){

    char **pz = &p->aOp[p->nOp-1].zComment;






    va_start(ap, zFormat);
    sqlite3DbFree(p->db, *pz);
    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
    va_end(ap);
  }
}
SQLITE_PRIVATE void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
  va_list ap;
  if( !p ) return;
  sqlite3VdbeAddOp0(p, OP_Noop);
  assert( p->nOp>0 || p->aOp==0 );
  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
  if( p->nOp ){
    char **pz = &p->aOp[p->nOp-1].zComment;
    va_start(ap, zFormat);
    sqlite3DbFree(p->db, *pz);
    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
    va_end(ap);
  }
}
#endif  /* NDEBUG */

/*
** Return the opcode for a given address.  If the address is -1, then
................................................................................
  int nRow;                            /* Stop when row count reaches this */
  int nSub = 0;                        /* Number of sub-vdbes seen so far */
  SubProgram **apSub = 0;              /* Array of sub-vdbes */
  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
  sqlite3 *db = p->db;                 /* The database connection */
  int i;                               /* Loop counter */
  int rc = SQLITE_OK;                  /* Return code */
  Mem *pMem = p->pResultSet = &p->aMem[1];  /* First Mem of result set */

  assert( p->explain );
  assert( p->magic==VDBE_MAGIC_RUN );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );

  /* Even though this opcode does not use dynamic strings for
  ** the result, result columns may become dynamic if the user calls
  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
  */
  releaseMemArray(pMem, 8);


  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */
    db->mallocFailed = 1;
    return SQLITE_ERROR;
  }
................................................................................
      {
        pMem->flags = MEM_Null;                       /* Comment */
        pMem->type = SQLITE_NULL;
      }
    }

    p->nResColumn = 8 - 4*(p->explain-1);

    p->rc = SQLITE_OK;
    rc = SQLITE_ROW;
  }
  return rc;
}
#endif /* SQLITE_OMIT_EXPLAIN */

................................................................................
/*
** Each VDBE holds the result of the most recent sqlite3_step() call
** in p->rc.  This routine sets that result back to SQLITE_OK.
*/
SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe *p){
  p->rc = SQLITE_OK;
}

























/*
** Clean up a VDBE after execution but do not delete the VDBE just yet.
** Write any error messages into *pzErrMsg.  Return the result code.
**
** After this routine is run, the VDBE should be ready to be executed
** again.
................................................................................

  /* If the VDBE has be run even partially, then transfer the error code
  ** and error message from the VDBE into the main database structure.  But
  ** if the VDBE has just been set to run but has not actually executed any
  ** instructions yet, leave the main database error information unchanged.
  */
  if( p->pc>=0 ){
    if( p->zErrMsg ){
      sqlite3BeginBenignMalloc();
      sqlite3ValueSetStr(db->pErr,-1,p->zErrMsg,SQLITE_UTF8,SQLITE_TRANSIENT);
      sqlite3EndBenignMalloc();
      db->errCode = p->rc;
      sqlite3DbFree(db, p->zErrMsg);
      p->zErrMsg = 0;
    }else if( p->rc ){
      sqlite3Error(db, p->rc, 0);
    }else{
      sqlite3Error(db, SQLITE_OK, 0);
    }
    if( p->runOnlyOnce ) p->expired = 1;
  }else if( p->rc && p->expired ){
    /* The expired flag was set on the VDBE before the first call
    ** to sqlite3_step(). For consistency (since sqlite3_step() was
    ** called), set the database error in this case as well.
    */
    sqlite3Error(db, p->rc, 0);
................................................................................

  /* Get the size of the index entry.  Only indices entries of less
  ** than 2GiB are support - anything large must be database corruption.
  ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
  ** this code can safely assume that nCellKey is 32-bits  
  */
  assert( sqlite3BtreeCursorIsValid(pCur) );
  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
  assert( rc==SQLITE_OK );     /* pCur is always valid so KeySize cannot fail */
  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );

  /* Read in the complete content of the index entry */
  memset(&m, 0, sizeof(m));
  rc = sqlite3VdbeMemFromBtree(pCur, 0, (int)nCellKey, 1, &m);
  if( rc ){
................................................................................
){
  i64 nCellKey = 0;
  int rc;
  BtCursor *pCur = pC->pCursor;
  Mem m;

  assert( sqlite3BtreeCursorIsValid(pCur) );
  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
  assert( rc==SQLITE_OK );    /* pCur is always valid so KeySize cannot fail */
  /* nCellKey will always be between 0 and 0xffffffff because of the say
  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
  if( nCellKey<=0 || nCellKey>0x7fffffff ){
    *res = 0;
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
  );
  assert( p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE );
  if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
    /* If this statement was prepared using sqlite3_prepare_v2(), and an
    ** error has occured, then return the error code in p->rc to the
    ** caller. Set the error code in the database handle to the same value.
    */ 
    rc = db->errCode = p->rc;
  }
  return (rc&db->errMask);
}

/*
** The maximum number of times that a statement will try to reparse
** itself before giving up and returning SQLITE_SCHEMA.
................................................................................
    if( u.am.pC->nullRow ){
      u.am.payloadSize = 0;
    }else if( u.am.pC->cacheStatus==p->cacheCtr ){
      u.am.payloadSize = u.am.pC->payloadSize;
      u.am.zRec = (char*)u.am.pC->aRow;
    }else if( u.am.pC->isIndex ){
      assert( sqlite3BtreeCursorIsValid(u.am.pCrsr) );
      rc = sqlite3BtreeKeySize(u.am.pCrsr, &u.am.payloadSize64);
      assert( rc==SQLITE_OK );   /* True because of CursorMoveto() call above */
      /* sqlite3BtreeParseCellPtr() uses getVarint32() to extract the
      ** payload size, so it is impossible for u.am.payloadSize64 to be
      ** larger than 32 bits. */
      assert( (u.am.payloadSize64 & SQLITE_MAX_U32)==(u64)u.am.payloadSize64 );
      u.am.payloadSize = (u32)u.am.payloadSize64;
    }else{
      assert( sqlite3BtreeCursorIsValid(u.am.pCrsr) );
      rc = sqlite3BtreeDataSize(u.am.pCrsr, &u.am.payloadSize);
      assert( rc==SQLITE_OK );   /* DataSize() cannot fail */
    }
  }else if( ALWAYS(u.am.pC->pseudoTableReg>0) ){
    u.am.pReg = &aMem[u.am.pC->pseudoTableReg];
    assert( u.am.pReg->flags & MEM_Blob );
    assert( memIsValid(u.am.pReg) );
    u.am.payloadSize = u.am.pReg->n;
................................................................................
  */
  assert( u.bk.pC->deferredMoveto==0 );
  rc = sqlite3VdbeCursorMoveto(u.bk.pC);
  if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;

  if( u.bk.pC->isIndex ){
    assert( !u.bk.pC->isTable );
    rc = sqlite3BtreeKeySize(u.bk.pCrsr, &u.bk.n64);
    assert( rc==SQLITE_OK );    /* True because of CursorMoveto() call above */
    if( u.bk.n64>db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
    u.bk.n = (u32)u.bk.n64;
  }else{
    rc = sqlite3BtreeDataSize(u.bk.pCrsr, &u.bk.n);
    assert( rc==SQLITE_OK );    /* DataSize() cannot fail */
    if( u.bk.n>(u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
  }
  if( sqlite3VdbeMemGrow(pOut, u.bk.n, 0) ){
    goto no_mem;
................................................................................
  int res;
#endif /* local variables moved into u.bn */

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  u.bn.pC = p->apCsr[pOp->p1];
  assert( u.bn.pC!=0 );
  u.bn.pCrsr = u.bn.pC->pCursor;
  if( NEVER(u.bn.pCrsr==0) ){
    u.bn.res = 1;
  }else{

    rc = sqlite3BtreeLast(u.bn.pCrsr, &u.bn.res);
  }
  u.bn.pC->nullRow = (u8)u.bn.res;
  u.bn.pC->deferredMoveto = 0;
  u.bn.pC->rowidIsValid = 0;
  u.bn.pC->cacheStatus = CACHE_STALE;
  if( pOp->p2>0 && u.bn.res ){
................................................................................
#ifndef SQLITE_OMIT_WAL
  u.ch.zFilename = sqlite3PagerFilename(u.ch.pPager);

  /* Do not allow a transition to journal_mode=WAL for a database
  ** in temporary storage or if the VFS does not support shared memory
  */
  if( u.ch.eNew==PAGER_JOURNALMODE_WAL
   && (u.ch.zFilename[0]==0                         /* Temp file */
       || !sqlite3PagerWalSupported(u.ch.pPager))   /* No shared-memory support */
  ){
    u.ch.eNew = u.ch.eOld;
  }

  if( (u.ch.eNew!=u.ch.eOld)
   && (u.ch.eOld==PAGER_JOURNALMODE_WAL || u.ch.eNew==PAGER_JOURNALMODE_WAL)
................................................................................

  u.co.pVtab = pOp->p4.pVtab->pVtab;
  u.co.pName = &aMem[pOp->p1];
  assert( u.co.pVtab->pModule->xRename );
  assert( memIsValid(u.co.pName) );
  REGISTER_TRACE(pOp->p1, u.co.pName);
  assert( u.co.pName->flags & MEM_Str );





  rc = u.co.pVtab->pModule->xRename(u.co.pVtab, u.co.pName->z);
  importVtabErrMsg(p, u.co.pVtab);
  p->expired = 0;

  break;
}
#endif

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VUpdate P1 P2 P3 P4 *
**
................................................................................
  ** allowing it to be repopulated by the memcpy() on the following line.
  */
  ExprSetProperty(pExpr, EP_Static);
  sqlite3ExprDelete(db, pExpr);
  memcpy(pExpr, pDup, sizeof(*pExpr));
  sqlite3DbFree(db, pDup);
}



















/*
** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
** that name in the set of source tables in pSrcList and make the pExpr 
** expression node refer back to that source column.  The following changes
** are made to pExpr:
**
................................................................................
          pExpr->iTable = pItem->iCursor;
          pExpr->pTab = pTab;
          pSchema = pTab->pSchema;
          pMatch = pItem;
        }
        for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
          if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
            IdList *pUsing;







            cnt++;
            pExpr->iTable = pItem->iCursor;
            pExpr->pTab = pTab;
            pMatch = pItem;
            pSchema = pTab->pSchema;
            /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
            pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;
            if( i<pSrcList->nSrc-1 ){
              if( pItem[1].jointype & JT_NATURAL ){
                /* If this match occurred in the left table of a natural join,
                ** then skip the right table to avoid a duplicate match */
                pItem++;
                i++;
              }else if( (pUsing = pItem[1].pUsing)!=0 ){
                /* If this match occurs on a column that is in the USING clause
                ** of a join, skip the search of the right table of the join
                ** to avoid a duplicate match there. */
                int k;
                for(k=0; k<pUsing->nId; k++){
                  if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){
                    pItem++;
                    i++;
                    break;
                  }
                }
              }
            }
            break;
          }
        }
      }
    }

#ifndef SQLITE_OMIT_TRIGGER
................................................................................
    if( pToken ){
      if( nExtra==0 ){
        pNew->flags |= EP_IntValue;
        pNew->u.iValue = iValue;
      }else{
        int c;
        pNew->u.zToken = (char*)&pNew[1];

        memcpy(pNew->u.zToken, pToken->z, pToken->n);
        pNew->u.zToken[pToken->n] = 0;
        if( dequote && nExtra>=3 
             && ((c = pToken->z[0])=='\'' || c=='"' || c=='[' || c=='`') ){
          sqlite3Dequote(pNew->u.zToken);
          if( c=='"' ) pNew->flags |= EP_DblQuoted;
        }
      }
................................................................................
  /* Check to see if an existing table or index can be used to
  ** satisfy the query.  This is preferable to generating a new 
  ** ephemeral table.
  */
  p = (ExprHasProperty(pX, EP_xIsSelect) ? pX->x.pSelect : 0);
  if( ALWAYS(pParse->nErr==0) && isCandidateForInOpt(p) ){
    sqlite3 *db = pParse->db;              /* Database connection */
    Expr *pExpr = p->pEList->a[0].pExpr;   /* Expression <column> */
    int iCol = pExpr->iColumn;             /* Index of column <column> */
    Vdbe *v = sqlite3GetVdbe(pParse);      /* Virtual machine being coded */


    Table *pTab = p->pSrc->a[0].pTab;      /* Table <table>. */
    int iDb;                               /* Database idx for pTab */








   
    /* Code an OP_VerifyCookie and OP_TableLock for <table>. */
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    sqlite3CodeVerifySchema(pParse, iDb);
    sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

    /* This function is only called from two places. In both cases the vdbe
................................................................................
  if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 2;
  if( ExprHasProperty(pA, EP_IntValue) ){
    if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){
      return 2;
    }
  }else if( pA->op!=TK_COLUMN && pA->u.zToken ){
    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 2;
    if( sqlite3StrICmp(pA->u.zToken,pB->u.zToken)!=0 ){
      return 2;
    }
  }
  if( (pA->flags & EP_ExpCollate)!=(pB->flags & EP_ExpCollate) ) return 1;
  if( (pA->flags & EP_ExpCollate)!=0 && pA->pColl!=pB->pColl ) return 2;
  return 0;
}
................................................................................
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code associated with the ANALYZE command.






































































































*/
#ifndef SQLITE_OMIT_ANALYZE

/*
** This routine generates code that opens the sqlite_stat1 table for
** writing with cursor iStatCur. If the library was built with the
** SQLITE_ENABLE_STAT2 macro defined, then the sqlite_stat2 table is
** opened for writing using cursor (iStatCur+1)
**
** If the sqlite_stat1 tables does not previously exist, it is created.
** Similarly, if the sqlite_stat2 table does not exist and the library
** is compiled with SQLITE_ENABLE_STAT2 defined, it is created. 
**
** Argument zWhere may be a pointer to a buffer containing a table name,
** or it may be a NULL pointer. If it is not NULL, then all entries in
** the sqlite_stat1 and (if applicable) sqlite_stat2 tables associated
** with the named table are deleted. If zWhere==0, then code is generated
** to delete all stat table entries.
*/
static void openStatTable(
  Parse *pParse,          /* Parsing context */
  int iDb,                /* The database we are looking in */
  int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
................................................................................
  const char *zWhereType  /* Either "tbl" or "idx" */
){
  static const struct {
    const char *zName;
    const char *zCols;
  } aTable[] = {
    { "sqlite_stat1", "tbl,idx,stat" },
#ifdef SQLITE_ENABLE_STAT2
    { "sqlite_stat2", "tbl,idx,sampleno,sample" },
#endif
  };

  int aRoot[] = {0, 0};
  u8 aCreateTbl[] = {0, 0};

  int i;
................................................................................
  Db *pDb;
  Vdbe *v = sqlite3GetVdbe(pParse);
  if( v==0 ) return;
  assert( sqlite3BtreeHoldsAllMutexes(db) );
  assert( sqlite3VdbeDb(v)==db );
  pDb = &db->aDb[iDb];




  for(i=0; i<ArraySize(aTable); i++){
    const char *zTab = aTable[i].zName;
    Table *pStat;
    if( (pStat = sqlite3FindTable(db, zTab, pDb->zName))==0 ){
      /* The sqlite_stat[12] table does not exist. Create it. Note that a 
      ** side-effect of the CREATE TABLE statement is to leave the rootpage 
      ** of the new table in register pParse->regRoot. This is important 
................................................................................
      }else{
        /* The sqlite_stat[12] table already exists.  Delete all rows. */
        sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
      }
    }
  }

  /* Open the sqlite_stat[12] tables for writing. */
  for(i=0; i<ArraySize(aTable); i++){
    sqlite3VdbeAddOp3(v, OP_OpenWrite, iStatCur+i, aRoot[i], iDb);
    sqlite3VdbeChangeP4(v, -1, (char *)3, P4_INT32);
    sqlite3VdbeChangeP5(v, aCreateTbl[i]);
  }
}





























































































































































































































/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
................................................................................
  int i;                       /* Loop counter */
  int topOfLoop;               /* The top of the loop */
  int endOfLoop;               /* The end of the loop */
  int jZeroRows = -1;          /* Jump from here if number of rows is zero */
  int iDb;                     /* Index of database containing pTab */
  int regTabname = iMem++;     /* Register containing table name */
  int regIdxname = iMem++;     /* Register containing index name */
  int regSampleno = iMem++;    /* Register containing next sample number */















  int regCol = iMem++;         /* Content of a column analyzed table */
  int regRec = iMem++;         /* Register holding completed record */
  int regTemp = iMem++;        /* Temporary use register */
  int regRowid = iMem++;       /* Rowid for the inserted record */

#ifdef SQLITE_ENABLE_STAT2
  int addr = 0;                /* Instruction address */
  int regTemp2 = iMem++;       /* Temporary use register */
  int regSamplerecno = iMem++; /* Index of next sample to record */
  int regRecno = iMem++;       /* Current sample index */
  int regLast = iMem++;        /* Index of last sample to record */
  int regFirst = iMem++;       /* Index of first sample to record */
#endif

  v = sqlite3GetVdbe(pParse);
  if( v==0 || NEVER(pTab==0) ){
    return;
  }
  if( pTab->tnum==0 ){
    /* Do not gather statistics on views or virtual tables */
................................................................................
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

  iIdxCur = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol;
    KeyInfo *pKey;



    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;

    nCol = pIdx->nColumn;


    pKey = sqlite3IndexKeyinfo(pParse, pIdx);
    if( iMem+1+(nCol*2)>pParse->nMem ){
      pParse->nMem = iMem+1+(nCol*2);
    }

    /* Open a cursor to the index to be analyzed. */
    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
................................................................................
    sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,
        (char *)pKey, P4_KEYINFO_HANDOFF);
    VdbeComment((v, "%s", pIdx->zName));

    /* Populate the register containing the index name. */
    sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, pIdx->zName, 0);

#ifdef SQLITE_ENABLE_STAT2


    /* If this iteration of the loop is generating code to analyze the
    ** first index in the pTab->pIndex list, then register regLast has
    ** not been populated. In this case populate it now.  */
    if( pTab->pIndex==pIdx ){
      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regSamplerecno);
      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2-1, regTemp);
      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2, regTemp2);

      sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regLast);
      sqlite3VdbeAddOp2(v, OP_Null, 0, regFirst);
      addr = sqlite3VdbeAddOp3(v, OP_Lt, regSamplerecno, 0, regLast);
      sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regFirst);
      sqlite3VdbeAddOp3(v, OP_Multiply, regLast, regTemp, regLast);
      sqlite3VdbeAddOp2(v, OP_AddImm, regLast, SQLITE_INDEX_SAMPLES*2-2);
      sqlite3VdbeAddOp3(v, OP_Divide,  regTemp2, regLast, regLast);
      sqlite3VdbeJumpHere(v, addr);
    }

    /* Zero the regSampleno and regRecno registers. */
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regSampleno);
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRecno);
    sqlite3VdbeAddOp2(v, OP_Copy, regFirst, regSamplerecno);
#endif





    /* The block of memory cells initialized here is used as follows.
    **
    **    iMem:                
    **        The total number of rows in the table.
    **
    **    iMem+1 .. iMem+nCol: 
................................................................................
    }

    /* Start the analysis loop. This loop runs through all the entries in
    ** the index b-tree.  */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);

    for(i=0; i<nCol; i++){
      CollSeq *pColl;
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
      if( i==0 ){
#ifdef SQLITE_ENABLE_STAT2
        /* Check if the record that cursor iIdxCur points to contains a
        ** value that should be stored in the sqlite_stat2 table. If so,
        ** store it.  */
        int ne = sqlite3VdbeAddOp3(v, OP_Ne, regRecno, 0, regSamplerecno);
        assert( regTabname+1==regIdxname 
             && regTabname+2==regSampleno
             && regTabname+3==regCol
        );
        sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
        sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 4, regRec, "aaab", 0);
        sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regRowid);
        sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regRowid);

        /* Calculate new values for regSamplerecno and regSampleno.
        **
        **   sampleno = sampleno + 1
        **   samplerecno = samplerecno+(remaining records)/(remaining samples)
        */
        sqlite3VdbeAddOp2(v, OP_AddImm, regSampleno, 1);
        sqlite3VdbeAddOp3(v, OP_Subtract, regRecno, regLast, regTemp);
        sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
        sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regTemp2);
        sqlite3VdbeAddOp3(v, OP_Subtract, regSampleno, regTemp2, regTemp2);
        sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regTemp, regTemp);
        sqlite3VdbeAddOp3(v, OP_Add, regSamplerecno, regTemp, regSamplerecno);

        sqlite3VdbeJumpHere(v, ne);
        sqlite3VdbeAddOp2(v, OP_AddImm, regRecno, 1);
#endif

        /* Always record the very first row */
        sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
      }
      assert( pIdx->azColl!=0 );
      assert( pIdx->azColl[i]!=0 );
      pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
      sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
                       (char*)pColl, P4_COLLSEQ);
      sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);





    }
    if( db->mallocFailed ){
      /* If a malloc failure has occurred, then the result of the expression 
      ** passed as the second argument to the call to sqlite3VdbeJumpHere() 
      ** below may be negative. Which causes an assert() to fail (or an
      ** out-of-bounds write if SQLITE_DEBUG is not defined).  */
      return;
    }
    sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      int addr2 = sqlite3VdbeCurrentAddr(v) - (nCol*2);
      if( i==0 ){
        sqlite3VdbeJumpHere(v, addr2-1);  /* Set jump dest for the OP_IfNot */









      }
      sqlite3VdbeJumpHere(v, addr2);      /* Set jump dest for the OP_Ne */
      sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);
    }


    /* End of the analysis loop. */

    sqlite3VdbeResolveLabel(v, endOfLoop);

    sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);






























    /* Store the results in sqlite_stat1.
    **
    ** The result is a single row of the sqlite_stat1 table.  The first
    ** two columns are the names of the table and index.  The third column
    ** is a string composed of a list of integer statistics about the
    ** index.  The first integer in the list is the total number of entries
................................................................................
    **
    **        I = (K+D-1)/D
    **
    ** If K==0 then no entry is made into the sqlite_stat1 table.  
    ** If K>0 then it is always the case the D>0 so division by zero
    ** is never possible.
    */
    sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regSampleno);
    if( jZeroRows<0 ){
      jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
      sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
      sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
      sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);
      sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
    }
    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  }

  /* If the table has no indices, create a single sqlite_stat1 entry
  ** containing NULL as the index name and the row count as the content.
  */
  if( pTab->pIndex==0 ){
    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
    VdbeComment((v, "%s", pTab->zName));
    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regSampleno);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regSampleno);
  }else{
    sqlite3VdbeJumpHere(v, jZeroRows);
    jZeroRows = sqlite3VdbeAddOp0(v, OP_Goto);
  }
  sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
  sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
  sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
  sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
  sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  if( pParse->nMem<regRec ) pParse->nMem = regRec;
  sqlite3VdbeJumpHere(v, jZeroRows);
}


/*
** Generate code that will cause the most recent index analysis to
** be loaded into internal hash tables where is can be used.
*/
static void loadAnalysis(Parse *pParse, int iDb){
  Vdbe *v = sqlite3GetVdbe(pParse);
................................................................................
  Schema *pSchema = db->aDb[iDb].pSchema;    /* Schema of database iDb */
  HashElem *k;
  int iStatCur;
  int iMem;

  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab;
  pParse->nTab += 2;
  openStatTable(pParse, iDb, iStatCur, 0, 0);
  iMem = pParse->nMem+1;
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
    Table *pTab = (Table*)sqliteHashData(k);
    analyzeOneTable(pParse, pTab, 0, iStatCur, iMem);
  }
................................................................................
  int iStatCur;

  assert( pTab!=0 );
  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab;
  pParse->nTab += 2;
  if( pOnlyIdx ){
    openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx");
  }else{
    openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl");
  }
  analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur, pParse->nMem+1);
  loadAnalysis(pParse, iDb);
................................................................................
** the table.
*/
static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
  analysisInfo *pInfo = (analysisInfo*)pData;
  Index *pIndex;
  Table *pTable;
  int i, c, n;
  unsigned int v;
  const char *z;

  assert( argc==3 );
  UNUSED_PARAMETER2(NotUsed, argc);

  if( argv==0 || argv[0]==0 || argv[2]==0 ){
    return 0;
................................................................................
}

/*
** If the Index.aSample variable is not NULL, delete the aSample[] array
** and its contents.
*/
SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){
#ifdef SQLITE_ENABLE_STAT2
  if( pIdx->aSample ){
    int j;
    for(j=0; j<SQLITE_INDEX_SAMPLES; j++){
      IndexSample *p = &pIdx->aSample[j];
      if( p->eType==SQLITE_TEXT || p->eType==SQLITE_BLOB ){
        sqlite3DbFree(db, p->u.z);
      }
    }
    sqlite3DbFree(db, pIdx->aSample);




  }
#else
  UNUSED_PARAMETER(db);
  UNUSED_PARAMETER(pIdx);
#endif
}


/*































































































































** Load the content of the sqlite_stat1 and sqlite_stat2 tables. The
** contents of sqlite_stat1 are used to populate the Index.aiRowEst[]
** arrays. The contents of sqlite_stat2 are used to populate the
** Index.aSample[] arrays.
**
** If the sqlite_stat1 table is not present in the database, SQLITE_ERROR
** is returned. In this case, even if SQLITE_ENABLE_STAT2 was defined 
** during compilation and the sqlite_stat2 table is present, no data is 
** read from it.
**
** If SQLITE_ENABLE_STAT2 was defined during compilation and the 
** sqlite_stat2 table is not present in the database, SQLITE_ERROR is
** returned. However, in this case, data is read from the sqlite_stat1
** table (if it is present) before returning.
**
** If an OOM error occurs, this function always sets db->mallocFailed.
** This means if the caller does not care about other errors, the return
** code may be ignored.
*/
................................................................................
  assert( db->aDb[iDb].pBt!=0 );

  /* Clear any prior statistics */
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    sqlite3DefaultRowEst(pIdx);

    sqlite3DeleteIndexSamples(db, pIdx);
    pIdx->aSample = 0;

  }

  /* Check to make sure the sqlite_stat1 table exists */
  sInfo.db = db;
  sInfo.zDatabase = db->aDb[iDb].zName;
  if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){
    return SQLITE_ERROR;
  }

  /* Load new statistics out of the sqlite_stat1 table */
  zSql = sqlite3MPrintf(db, 
      "SELECT tbl, idx, stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
  if( zSql==0 ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
    sqlite3DbFree(db, zSql);
  }


  /* Load the statistics from the sqlite_stat2 table. */
#ifdef SQLITE_ENABLE_STAT2
  if( rc==SQLITE_OK && !sqlite3FindTable(db, "sqlite_stat2", sInfo.zDatabase) ){
    rc = SQLITE_ERROR;
  }
  if( rc==SQLITE_OK ){
    sqlite3_stmt *pStmt = 0;

    zSql = sqlite3MPrintf(db, 
        "SELECT idx,sampleno,sample FROM %Q.sqlite_stat2", sInfo.zDatabase);
    if( !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
      sqlite3DbFree(db, zSql);
    }

    if( rc==SQLITE_OK ){
      while( sqlite3_step(pStmt)==SQLITE_ROW ){
        char *zIndex;   /* Index name */
        Index *pIdx;    /* Pointer to the index object */

        zIndex = (char *)sqlite3_column_text(pStmt, 0);
        pIdx = zIndex ? sqlite3FindIndex(db, zIndex, sInfo.zDatabase) : 0;
        if( pIdx ){
          int iSample = sqlite3_column_int(pStmt, 1);
          if( iSample<SQLITE_INDEX_SAMPLES && iSample>=0 ){
            int eType = sqlite3_column_type(pStmt, 2);

            if( pIdx->aSample==0 ){
              static const int sz = sizeof(IndexSample)*SQLITE_INDEX_SAMPLES;
              pIdx->aSample = (IndexSample *)sqlite3DbMallocRaw(0, sz);
              if( pIdx->aSample==0 ){
                db->mallocFailed = 1;
                break;
              }
	      memset(pIdx->aSample, 0, sz);
            }

            assert( pIdx->aSample );
            {
              IndexSample *pSample = &pIdx->aSample[iSample];
              pSample->eType = (u8)eType;
              if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
                pSample->u.r = sqlite3_column_double(pStmt, 2);
              }else if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
                const char *z = (const char *)(
                    (eType==SQLITE_BLOB) ?
                    sqlite3_column_blob(pStmt, 2):
                    sqlite3_column_text(pStmt, 2)
                );
                int n = sqlite3_column_bytes(pStmt, 2);
                if( n>24 ){
                  n = 24;
                }
                pSample->nByte = (u8)n;
                if( n < 1){
                  pSample->u.z = 0;
                }else{
                  pSample->u.z = sqlite3DbStrNDup(0, z, n);
                  if( pSample->u.z==0 ){
                    db->mallocFailed = 1;
                    break;
                  }
                }
              }
            }
          }
        }
      }
      rc = sqlite3_finalize(pStmt);
    }
  }
#endif

  if( rc==SQLITE_NOMEM ){
    db->mallocFailed = 1;
  }
  return rc;
................................................................................
      iDestroyed = iLargest;
    }
  }
#endif
}

/*
** Remove entries from the sqlite_stat1 and sqlite_stat2 tables
** after a DROP INDEX or DROP TABLE command.
*/
static void sqlite3ClearStatTables(
  Parse *pParse,         /* The parsing context */
  int iDb,               /* The database number */
  const char *zType,     /* "idx" or "tbl" */
  const char *zName      /* Name of index or table */
){
  static const char *azStatTab[] = { "sqlite_stat1", "sqlite_stat2" };
  int i;
  const char *zDbName = pParse->db->aDb[iDb].zName;

  for(i=0; i<ArraySize(azStatTab); i++){

    if( sqlite3FindTable(pParse->db, azStatTab[i], zDbName) ){
      sqlite3NestedParse(pParse,
        "DELETE FROM %Q.%s WHERE %s=%Q",
        zDbName, azStatTab[i], zType, zName

      );
    }
  }
}







































































/*
** This routine is called to do the work of a DROP TABLE statement.
** pName is the name of the table to be dropped.
*/
SQLITE_PRIVATE void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
  Table *pTab;
................................................................................
      goto exit_drop_table;
    }
    if( sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){
      goto exit_drop_table;
    }
  }
#endif
  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){

    sqlite3ErrorMsg(pParse, "table %s may not be dropped", pTab->zName);
    goto exit_drop_table;
  }

#ifndef SQLITE_OMIT_VIEW
  /* Ensure DROP TABLE is not used on a view, and DROP VIEW is not used
  ** on a table.
................................................................................
#endif

  /* Generate code to remove the table from the master table
  ** on disk.
  */
  v = sqlite3GetVdbe(pParse);
  if( v ){
    Trigger *pTrigger;
    Db *pDb = &db->aDb[iDb];
    sqlite3BeginWriteOperation(pParse, 1, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( IsVirtual(pTab) ){
      sqlite3VdbeAddOp0(v, OP_VBegin);
    }
#endif
    sqlite3FkDropTable(pParse, pName, pTab);

    /* Drop all triggers associated with the table being dropped. Code
    ** is generated to remove entries from sqlite_master and/or
    ** sqlite_temp_master if required.
    */
    pTrigger = sqlite3TriggerList(pParse, pTab);
    while( pTrigger ){
      assert( pTrigger->pSchema==pTab->pSchema || 
          pTrigger->pSchema==db->aDb[1].pSchema );
      sqlite3DropTriggerPtr(pParse, pTrigger);
      pTrigger = pTrigger->pNext;
    }

#ifndef SQLITE_OMIT_AUTOINCREMENT
    /* Remove any entries of the sqlite_sequence table associated with
    ** the table being dropped. This is done before the table is dropped
    ** at the btree level, in case the sqlite_sequence table needs to
    ** move as a result of the drop (can happen in auto-vacuum mode).
    */
    if( pTab->tabFlags & TF_Autoincrement ){
      sqlite3NestedParse(pParse,
        "DELETE FROM %s.sqlite_sequence WHERE name=%Q",
        pDb->zName, pTab->zName
      );
    }
#endif

    /* Drop all SQLITE_MASTER table and index entries that refer to the
    ** table. The program name loops through the master table and deletes
    ** every row that refers to a table of the same name as the one being
    ** dropped. Triggers are handled seperately because a trigger can be
    ** created in the temp database that refers to a table in another
    ** database.
    */
    sqlite3NestedParse(pParse, 
        "DELETE FROM %Q.%s WHERE tbl_name=%Q and type!='trigger'",
        pDb->zName, SCHEMA_TABLE(iDb), pTab->zName);
    sqlite3ClearStatTables(pParse, iDb, "tbl", pTab->zName);
    if( !isView && !IsVirtual(pTab) ){

      destroyTable(pParse, pTab);
    }

    /* Remove the table entry from SQLite's internal schema and modify
    ** the schema cookie.
    */
    if( IsVirtual(pTab) ){
      sqlite3VdbeAddOp4(v, OP_VDestroy, iDb, 0, 0, pTab->zName, 0);
    }
    sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);
    sqlite3ChangeCookie(pParse, iDb);
  }
  sqliteViewResetAll(db, iDb);

exit_drop_table:
  sqlite3SrcListDelete(db, pName);
}

/*
** This routine is called to create a new foreign key on the table
................................................................................
** the index already exists and must be cleared before being refilled and
** the root page number of the index is taken from pIndex->tnum.
*/
static void sqlite3RefillIndex(Parse *pParse, Index *pIndex, int memRootPage){
  Table *pTab = pIndex->pTable;  /* The table that is indexed */
  int iTab = pParse->nTab++;     /* Btree cursor used for pTab */
  int iIdx = pParse->nTab++;     /* Btree cursor used for pIndex */
  int iSorter = iTab;            /* Cursor opened by OpenSorter (if in use) */
  int addr1;                     /* Address of top of loop */
  int addr2;                     /* Address to jump to for next iteration */
  int tnum;                      /* Root page of index */
  Vdbe *v;                       /* Generate code into this virtual machine */
  KeyInfo *pKey;                 /* KeyInfo for index */

  int regIdxKey;                 /* Registers containing the index key */

  int regRecord;                 /* Register holding assemblied index record */
  sqlite3 *db = pParse->db;      /* The database connection */
  int iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);

#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_REINDEX, pIndex->zName, 0,
      db->aDb[iDb].zName ) ){
................................................................................
    sqlite3VdbeChangeP5(v, 1);
  }

#ifndef SQLITE_OMIT_MERGE_SORT
  /* Open the sorter cursor if we are to use one. */
  iSorter = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_SorterOpen, iSorter, 0, 0, (char*)pKey, P4_KEYINFO);


#endif

  /* Open the table. Loop through all rows of the table, inserting index
  ** records into the sorter. */
  sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
  addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);
  addr2 = addr1 + 1;
  regRecord = sqlite3GetTempReg(pParse);
  regIdxKey = sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);

#ifndef SQLITE_OMIT_MERGE_SORT

  sqlite3VdbeAddOp2(v, OP_SorterInsert, iSorter, regRecord);
  sqlite3VdbeAddOp2(v, OP_Next, iTab, addr1+1);
  sqlite3VdbeJumpHere(v, addr1);
  addr1 = sqlite3VdbeAddOp2(v, OP_SorterSort, iSorter, 0);
  if( pIndex->onError!=OE_None ){
    int j2 = sqlite3VdbeCurrentAddr(v) + 3;
    sqlite3VdbeAddOp2(v, OP_Goto, 0, j2);
................................................................................
  }else{
    addr2 = sqlite3VdbeCurrentAddr(v);
  }
  sqlite3VdbeAddOp2(v, OP_SorterData, iSorter, regRecord);
  sqlite3VdbeAddOp3(v, OP_IdxInsert, iIdx, regRecord, 1);
  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
#else


  if( pIndex->onError!=OE_None ){
    const int regRowid = regIdxKey + pIndex->nColumn;
    const int j2 = sqlite3VdbeCurrentAddr(v) + 2;
    void * const pRegKey = SQLITE_INT_TO_PTR(regIdxKey);

    /* The registers accessed by the OP_IsUnique opcode were allocated
    ** using sqlite3GetTempRange() inside of the sqlite3GenerateIndexKey()
................................................................................
    /* Use the two-part index name to determine the database 
    ** to search for the table. 'Fix' the table name to this db
    ** before looking up the table.
    */
    assert( pName1 && pName2 );
    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
    if( iDb<0 ) goto exit_create_index;


#ifndef SQLITE_OMIT_TEMPDB
    /* If the index name was unqualified, check if the the table
    ** is a temp table. If so, set the database to 1. Do not do this
    ** if initialising a database schema.
    */
    if( !db->init.busy ){
................................................................................
    }
    pTab = sqlite3LocateTable(pParse, 0, pTblName->a[0].zName, 
        pTblName->a[0].zDatabase);
    if( !pTab || db->mallocFailed ) goto exit_create_index;
    assert( db->aDb[iDb].pSchema==pTab->pSchema );
  }else{
    assert( pName==0 );

    pTab = pParse->pNewTable;
    if( !pTab ) goto exit_create_index;
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  }
  pDb = &db->aDb[iDb];

  assert( pTab!=0 );
................................................................................
  ** If pName==0 it means that we are
  ** dealing with a primary key or UNIQUE constraint.  We have to invent our
  ** own name.
  */
  if( pName ){
    zName = sqlite3NameFromToken(db, pName);
    if( zName==0 ) goto exit_create_index;

    if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
      goto exit_create_index;
    }
    if( !db->init.busy ){
      if( sqlite3FindTable(db, zName, 0)!=0 ){
        sqlite3ErrorMsg(pParse, "there is already a table named %s", zName);
        goto exit_create_index;
................................................................................
  /* 
  ** Allocate the index structure. 
  */
  nName = sqlite3Strlen30(zName);
  nCol = pList->nExpr;
  pIndex = sqlite3DbMallocZero(db, 
      sizeof(Index) +              /* Index structure  */

      sizeof(int)*nCol +           /* Index.aiColumn   */
      sizeof(int)*(nCol+1) +       /* Index.aiRowEst   */
      sizeof(char *)*nCol +        /* Index.azColl     */
      sizeof(u8)*nCol +            /* Index.aSortOrder */
      nName + 1 +                  /* Index.zName      */
      nExtra                       /* Collation sequence names */
  );
  if( db->mallocFailed ){
    goto exit_create_index;
  }

  pIndex->azColl = (char**)(&pIndex[1]);
  pIndex->aiColumn = (int *)(&pIndex->azColl[nCol]);
  pIndex->aiRowEst = (unsigned *)(&pIndex->aiColumn[nCol]);
  pIndex->aSortOrder = (u8 *)(&pIndex->aiRowEst[nCol+1]);
  pIndex->zName = (char *)(&pIndex->aSortOrder[nCol]);
  zExtra = (char *)(&pIndex->zName[nName+1]);
  memcpy(pIndex->zName, zName, nName+1);
  pIndex->pTable = pTab;
  pIndex->nColumn = pList->nExpr;
  pIndex->onError = (u8)onError;
  pIndex->autoIndex = (u8)(pName==0);
................................................................................
**           aiRowEst[N]>=1
**
** Apart from that, we have little to go on besides intuition as to
** how aiRowEst[] should be initialized.  The numbers generated here
** are based on typical values found in actual indices.
*/
SQLITE_PRIVATE void sqlite3DefaultRowEst(Index *pIdx){
  unsigned *a = pIdx->aiRowEst;
  int i;
  unsigned n;
  assert( a!=0 );
  a[0] = pIdx->pTable->nRowEst;
  if( a[0]<10 ) a[0] = 10;
  n = 10;
  for(i=1; i<=pIdx->nColumn; i++){
    a[i] = n;
    if( n>5 ) n--;
................................................................................
  sqlite3VdbeAddOp2(v, OP_AutoCommit, 0, 0);
}

/*
** Commit a transaction
*/
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse *pParse){
  sqlite3 *db;
  Vdbe *v;

  assert( pParse!=0 );
  db = pParse->db;
  assert( db!=0 );
/*  if( db->aDb[0].pBt==0 ) return; */
  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "COMMIT", 0, 0) ){
    return;
  }
  v = sqlite3GetVdbe(pParse);
  if( v ){
    sqlite3VdbeAddOp2(v, OP_AutoCommit, 1, 0);
  }
}

/*
** Rollback a transaction
*/
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse *pParse){
  sqlite3 *db;
  Vdbe *v;

  assert( pParse!=0 );
  db = pParse->db;
  assert( db!=0 );
/*  if( db->aDb[0].pBt==0 ) return; */
  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "ROLLBACK", 0, 0) ){
    return;
  }
  v = sqlite3GetVdbe(pParse);
  if( v ){
    sqlite3VdbeAddOp2(v, OP_AutoCommit, 1, 1);
  }
................................................................................
  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){
      memcpy(z1, z2, n+1);
      for(i=0; z1[i]; i++){
        z1[i] = (char)sqlite3Toupper(z1[i]);
      }
      sqlite3_result_text(context, z1, -1, sqlite3_free);
    }
  }
}
static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  u8 *z1;
  const char *z2;
  int i, n;
  UNUSED_PARAMETER(argc);
  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){
      memcpy(z1, z2, n+1);
      for(i=0; z1[i]; i++){
        z1[i] = sqlite3Tolower(z1[i]);
      }
      sqlite3_result_text(context, (char *)z1, -1, sqlite3_free);
    }
  }
}


#if 0  /* This function is never used. */
/*
................................................................................
    sqlite3ExprDelete(db, pWhen);
    sqlite3ExprListDelete(db, pList);
    sqlite3SelectDelete(db, pSelect);
    if( db->mallocFailed==1 ){
      fkTriggerDelete(db, pTrigger);
      return 0;
    }


    switch( action ){
      case OE_Restrict:
        pStep->op = TK_SELECT; 
        break;
      case OE_Cascade: 
        if( !pChanges ){ 
................................................................................
  ** the extra complication to make this rule less restrictive is probably
  ** not worth the effort.  Ticket [6284df89debdfa61db8073e062908af0c9b6118e]
  */
  if( (pParse->db->flags & SQLITE_ForeignKeys)!=0 && pDest->pFKey!=0 ){
    return 0;
  }
#endif




  /* If we get this far, it means either:
  **
  **    *   We can always do the transfer if the table contains an
  **        an integer primary key
  **
  **    *   We can conditionally do the transfer if the destination
................................................................................
  int  (*bind_text)(sqlite3_stmt*,int,const char*,int n,void(*)(void*));
  int  (*bind_text16)(sqlite3_stmt*,int,const void*,int,void(*)(void*));
  int  (*bind_value)(sqlite3_stmt*,int,const sqlite3_value*);
  int  (*busy_handler)(sqlite3*,int(*)(void*,int),void*);
  int  (*busy_timeout)(sqlite3*,int ms);
  int  (*changes)(sqlite3*);
  int  (*close)(sqlite3*);
  int  (*collation_needed)(sqlite3*,void*,void(*)(void*,sqlite3*,int eTextRep,const char*));

  int  (*collation_needed16)(sqlite3*,void*,void(*)(void*,sqlite3*,int eTextRep,const void*));

  const void * (*column_blob)(sqlite3_stmt*,int iCol);
  int  (*column_bytes)(sqlite3_stmt*,int iCol);
  int  (*column_bytes16)(sqlite3_stmt*,int iCol);
  int  (*column_count)(sqlite3_stmt*pStmt);
  const char * (*column_database_name)(sqlite3_stmt*,int);
  const void * (*column_database_name16)(sqlite3_stmt*,int);
  const char * (*column_decltype)(sqlite3_stmt*,int i);
................................................................................
  const unsigned char * (*column_text)(sqlite3_stmt*,int iCol);
  const void * (*column_text16)(sqlite3_stmt*,int iCol);
  int  (*column_type)(sqlite3_stmt*,int iCol);
  sqlite3_value* (*column_value)(sqlite3_stmt*,int iCol);
  void * (*commit_hook)(sqlite3*,int(*)(void*),void*);
  int  (*complete)(const char*sql);
  int  (*complete16)(const void*sql);
  int  (*create_collation)(sqlite3*,const char*,int,void*,int(*)(void*,int,const void*,int,const void*));

  int  (*create_collation16)(sqlite3*,const void*,int,void*,int(*)(void*,int,const void*,int,const void*));

  int  (*create_function)(sqlite3*,const char*,int,int,void*,void (*xFunc)(sqlite3_context*,int,sqlite3_value**),void (*xStep)(sqlite3_context*,int,sqlite3_value**),void (*xFinal)(sqlite3_context*));



  int  (*create_function16)(sqlite3*,const void*,int,int,void*,void (*xFunc)(sqlite3_context*,int,sqlite3_value**),void (*xStep)(sqlite3_context*,int,sqlite3_value**),void (*xFinal)(sqlite3_context*));



  int (*create_module)(sqlite3*,const char*,const sqlite3_module*,void*);
  int  (*data_count)(sqlite3_stmt*pStmt);
  sqlite3 * (*db_handle)(sqlite3_stmt*);
  int (*declare_vtab)(sqlite3*,const char*);
  int  (*enable_shared_cache)(int);
  int  (*errcode)(sqlite3*db);
  const char * (*errmsg)(sqlite3*);
................................................................................
  void  (*result_null)(sqlite3_context*);
  void  (*result_text)(sqlite3_context*,const char*,int,void(*)(void*));
  void  (*result_text16)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_text16be)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_text16le)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_value)(sqlite3_context*,sqlite3_value*);
  void * (*rollback_hook)(sqlite3*,void(*)(void*),void*);
  int  (*set_authorizer)(sqlite3*,int(*)(void*,int,const char*,const char*,const char*,const char*),void*);

  void  (*set_auxdata)(sqlite3_context*,int,void*,void (*)(void*));
  char * (*snprintf)(int,char*,const char*,...);
  int  (*step)(sqlite3_stmt*);
  int  (*table_column_metadata)(sqlite3*,const char*,const char*,const char*,char const**,char const**,int*,int*,int*);

  void  (*thread_cleanup)(void);
  int  (*total_changes)(sqlite3*);
  void * (*trace)(sqlite3*,void(*xTrace)(void*,const char*),void*);
  int  (*transfer_bindings)(sqlite3_stmt*,sqlite3_stmt*);
  void * (*update_hook)(sqlite3*,void(*)(void*,int ,char const*,char const*,sqlite_int64),void*);

  void * (*user_data)(sqlite3_context*);
  const void * (*value_blob)(sqlite3_value*);
  int  (*value_bytes)(sqlite3_value*);
  int  (*value_bytes16)(sqlite3_value*);
  double  (*value_double)(sqlite3_value*);
  int  (*value_int)(sqlite3_value*);
  sqlite_int64  (*value_int64)(sqlite3_value*);
................................................................................
  /* Added ??? */
  int (*overload_function)(sqlite3*, const char *zFuncName, int nArg);
  /* Added by 3.3.13 */
  int (*prepare_v2)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
  int (*prepare16_v2)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
  int (*clear_bindings)(sqlite3_stmt*);
  /* Added by 3.4.1 */
  int (*create_module_v2)(sqlite3*,const char*,const sqlite3_module*,void*,void (*xDestroy)(void *));

  /* Added by 3.5.0 */
  int (*bind_zeroblob)(sqlite3_stmt*,int,int);
  int (*blob_bytes)(sqlite3_blob*);
  int (*blob_close)(sqlite3_blob*);
  int (*blob_open)(sqlite3*,const char*,const char*,const char*,sqlite3_int64,int,sqlite3_blob**);

  int (*blob_read)(sqlite3_blob*,void*,int,int);
  int (*blob_write)(sqlite3_blob*,const void*,int,int);
  int (*create_collation_v2)(sqlite3*,const char*,int,void*,int(*)(void*,int,const void*,int,const void*),void(*)(void*));


  int (*file_control)(sqlite3*,const char*,int,void*);
  sqlite3_int64 (*memory_highwater)(int);
  sqlite3_int64 (*memory_used)(void);
  sqlite3_mutex *(*mutex_alloc)(int);
  void (*mutex_enter)(sqlite3_mutex*);
  void (*mutex_free)(sqlite3_mutex*);
  void (*mutex_leave)(sqlite3_mutex*);
................................................................................
  int (*backup_finish)(sqlite3_backup*);
  sqlite3_backup *(*backup_init)(sqlite3*,const char*,sqlite3*,const char*);
  int (*backup_pagecount)(sqlite3_backup*);
  int (*backup_remaining)(sqlite3_backup*);
  int (*backup_step)(sqlite3_backup*,int);
  const char *(*compileoption_get)(int);
  int (*compileoption_used)(const char*);
  int (*create_function_v2)(sqlite3*,const char*,int,int,void*,void (*xFunc)(sqlite3_context*,int,sqlite3_value**),void (*xStep)(sqlite3_context*,int,sqlite3_value**),void (*xFinal)(sqlite3_context*),void(*xDestroy)(void*));




  int (*db_config)(sqlite3*,int,...);
  sqlite3_mutex *(*db_mutex)(sqlite3*);
  int (*db_status)(sqlite3*,int,int*,int*,int);
  int (*extended_errcode)(sqlite3*);
  void (*log)(int,const char*,...);
  sqlite3_int64 (*soft_heap_limit64)(sqlite3_int64);
  const char *(*sourceid)(void);
................................................................................
  char **pzErrMsg       /* Put error message here if not 0 */
){
  sqlite3_vfs *pVfs = db->pVfs;
  void *handle;
  int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
  char *zErrmsg = 0;
  void **aHandle;
  const int nMsg = 300;

  if( pzErrMsg ) *pzErrMsg = 0;

  /* Ticket #1863.  To avoid a creating security problems for older
  ** applications that relink against newer versions of SQLite, the
  ** ability to run load_extension is turned off by default.  One
  ** must call sqlite3_enable_load_extension() to turn on extension
................................................................................
    }
    return SQLITE_ERROR;
  }
  xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
                   sqlite3OsDlSym(pVfs, handle, zProc);
  if( xInit==0 ){
    if( pzErrMsg ){

      *pzErrMsg = zErrmsg = sqlite3_malloc(nMsg);
      if( zErrmsg ){
        sqlite3_snprintf(nMsg, zErrmsg,
            "no entry point [%s] in shared library [%s]", zProc,zFile);
        sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
      }
      sqlite3OsDlClose(pVfs, handle);
................................................................................
  if( sqlite3StrICmp(zLeft,"page_count")==0
   || sqlite3StrICmp(zLeft,"max_page_count")==0
  ){
    int iReg;
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
    sqlite3CodeVerifySchema(pParse, iDb);
    iReg = ++pParse->nMem;
    if( zLeft[0]=='p' ){
      sqlite3VdbeAddOp2(v, OP_Pagecount, iDb, iReg);
    }else{
      sqlite3VdbeAddOp3(v, OP_MaxPgcnt, iDb, iReg, sqlite3Atoi(zRight));
    }
    sqlite3VdbeAddOp2(v, OP_ResultRow, iReg, 1);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLeft, SQLITE_TRANSIENT);
................................................................................
  **  PRAGMA [database.]journal_mode =
  **                      (delete|persist|off|truncate|memory|wal|off)
  */
  if( sqlite3StrICmp(zLeft,"journal_mode")==0 ){
    int eMode;        /* One of the PAGER_JOURNALMODE_XXX symbols */
    int ii;           /* Loop counter */

    /* Force the schema to be loaded on all databases.  This cases all
    ** database files to be opened and the journal_modes set. */


    if( sqlite3ReadSchema(pParse) ){
      goto pragma_out;
    }

    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "journal_mode", SQLITE_STATIC);

................................................................................
    static const VdbeOpList endCode[] = {
      { OP_AddImm,      1, 0,        0},    /* 0 */
      { OP_IfNeg,       1, 0,        0},    /* 1 */
      { OP_String8,     0, 3,        0},    /* 2 */
      { OP_ResultRow,   3, 1,        0},
    };

    int isQuick = (zLeft[0]=='q');

    /* Initialize the VDBE program */
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
    pParse->nMem = 6;
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "integrity_check", SQLITE_STATIC);

................................................................................
){
  Select *pNew;
  Select standin;
  sqlite3 *db = pParse->db;
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
  assert( db->mallocFailed || !pOffset || pLimit ); /* OFFSET implies LIMIT */
  if( pNew==0 ){

    pNew = &standin;
    memset(pNew, 0, sizeof(*pNew));
  }
  if( pEList==0 ){
    pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0));
  }
  pNew->pEList = pEList;
................................................................................
  if( db->mallocFailed ) {
    clearSelect(db, pNew);
    if( pNew!=&standin ) sqlite3DbFree(db, pNew);
    pNew = 0;
  }else{
    assert( pNew->pSrc!=0 || pParse->nErr>0 );
  }

  return pNew;
}

/*
** Delete the given Select structure and all of its substructures.
*/
SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3 *db, Select *p){
................................................................................
               || p->pRight->u.zToken==0 || p->pRight->u.zToken[0]!=0 );
    if( (zName = pEList->a[i].zName)!=0 ){
      /* If the column contains an "AS <name>" phrase, use <name> as the name */
      zName = sqlite3DbStrDup(db, zName);
    }else{
      Expr *pColExpr = p;  /* The expression that is the result column name */
      Table *pTab;         /* Table associated with this expression */
      while( pColExpr->op==TK_DOT ) pColExpr = pColExpr->pRight;



      if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){
        /* For columns use the column name name */
        int iCol = pColExpr->iColumn;
        pTab = pColExpr->pTab;
        if( iCol<0 ) iCol = pTab->iPKey;
        zName = sqlite3MPrintf(db, "%s",
                 iCol>=0 ? pTab->aCol[iCol].zName : "rowid");
................................................................................
        if( pIdx->onError==OE_Replace ){
          openAll = 1;
          break;
        }
      }
    }
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){

      if( openAll || aRegIdx[i]>0 ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
                       (char*)pKey, P4_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }
................................................................................
  ** all record selected by the WHERE clause have been updated.
  */
  sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
  sqlite3VdbeJumpHere(v, addr);

  /* Close all tables */
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){

    if( openAll || aRegIdx[i]>0 ){
      sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0);
    }
  }
  sqlite3VdbeAddOp2(v, OP_Close, iCur, 0);

  /* Update the sqlite_sequence table by storing the content of the
................................................................................
    return SQLITE_NOMEM;
  }
  if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
    return sqlite3_errcode(db);
  }
  VVA_ONLY( rc = ) sqlite3_step(pStmt);
  assert( rc!=SQLITE_ROW );
  return vacuumFinalize(db, pStmt, pzErrMsg);
}

/*
** Execute zSql on database db. The statement returns exactly
** one column. Execute this as SQL on the same database.
*/
................................................................................
      "  SELECT type, name, tbl_name, rootpage, sql"
      "    FROM main.sqlite_master"
      "   WHERE type='view' OR type='trigger'"
      "      OR (type='table' AND rootpage=0)"
  );
  if( rc ) goto end_of_vacuum;

  /* At this point, unless the main db was completely empty, there is now a
  ** transaction open on the vacuum database, but not on the main database.
  ** Open a btree level transaction on the main database. This allows a

  ** call to sqlite3BtreeCopyFile(). The main database btree level
  ** transaction is then committed, so the SQL level never knows it was
  ** opened for writing. This way, the SQL transaction used to create the
  ** temporary database never needs to be committed.
  */
  {
    u32 meta;
    int i;

    /* This array determines which meta meta values are preserved in the
    ** vacuum.  Even entries are the meta value number and odd entries
................................................................................
  assert( op==SAVEPOINT_RELEASE||op==SAVEPOINT_ROLLBACK||op==SAVEPOINT_BEGIN );
  assert( iSavepoint>=0 );
  if( db->aVTrans ){
    int i;
    for(i=0; rc==SQLITE_OK && i<db->nVTrans; i++){
      VTable *pVTab = db->aVTrans[i];
      const sqlite3_module *pMod = pVTab->pMod->pModule;
      if( pMod->iVersion>=2 ){
        int (*xMethod)(sqlite3_vtab *, int);
        switch( op ){
          case SAVEPOINT_BEGIN:
            xMethod = pMod->xSavepoint;
            pVTab->iSavepoint = iSavepoint+1;
            break;
          case SAVEPOINT_ROLLBACK:
................................................................................
            xMethod = pMod->xRollbackTo;
            break;
          default:
            xMethod = pMod->xRelease;
            break;
        }
        if( xMethod && pVTab->iSavepoint>iSavepoint ){
          rc = xMethod(db->aVTrans[i]->pVtab, iSavepoint);
        }
      }
    }
  }
  return rc;
}

................................................................................
#define TERM_DYNAMIC    0x01   /* Need to call sqlite3ExprDelete(db, pExpr) */
#define TERM_VIRTUAL    0x02   /* Added by the optimizer.  Do not code */
#define TERM_CODED      0x04   /* This term is already coded */
#define TERM_COPIED     0x08   /* Has a child */
#define TERM_ORINFO     0x10   /* Need to free the WhereTerm.u.pOrInfo object */
#define TERM_ANDINFO    0x20   /* Need to free the WhereTerm.u.pAndInfo obj */
#define TERM_OR_OK      0x40   /* Used during OR-clause processing */
#ifdef SQLITE_ENABLE_STAT2
#  define TERM_VNULL    0x80   /* Manufactured x>NULL or x<=NULL term */
#else
#  define TERM_VNULL    0x00   /* Disabled if not using stat2 */
#endif

/*
** An instance of the following structure holds all information about a
** WHERE clause.  Mostly this is a container for one or more WhereTerms.








*/
struct WhereClause {
  Parse *pParse;           /* The parser context */
  WhereMaskSet *pMaskSet;  /* Mapping of table cursor numbers to bitmasks */
  Bitmask vmask;           /* Bitmask identifying virtual table cursors */

  u8 op;                   /* Split operator.  TK_AND or TK_OR */

  int nTerm;               /* Number of terms */
  int nSlot;               /* Number of entries in a[] */
  WhereTerm *a;            /* Each a[] describes a term of the WHERE cluase */
#if defined(SQLITE_SMALL_STACK)
  WhereTerm aStatic[1];    /* Initial static space for a[] */
#else
  WhereTerm aStatic[8];    /* Initial static space for a[] */
................................................................................

/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */
  WhereMaskSet *pMaskSet   /* Mapping from table cursor numbers to bitmasks */

){
  pWC->pParse = pParse;
  pWC->pMaskSet = pMaskSet;

  pWC->nTerm = 0;
  pWC->nSlot = ArraySize(pWC->aStatic);
  pWC->a = pWC->aStatic;
  pWC->vmask = 0;

}

/* Forward reference */
static void whereClauseClear(WhereClause*);

/*
** Deallocate all memory associated with a WhereOrInfo object.
................................................................................
  u32 op,               /* Mask of WO_xx values describing operator */
  Index *pIdx           /* Must be compatible with this index, if not NULL */
){
  WhereTerm *pTerm;
  int k;
  assert( iCur>=0 );
  op &= WO_ALL;

  for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
    if( pTerm->leftCursor==iCur
       && (pTerm->prereqRight & notReady)==0
       && pTerm->u.leftColumn==iColumn
       && (pTerm->eOperator & op)!=0
    ){
      if( pIdx && pTerm->eOperator!=WO_ISNULL ){
        Expr *pX = pTerm->pExpr;
        CollSeq *pColl;
        char idxaff;
        int j;
        Parse *pParse = pWC->pParse;

        idxaff = pIdx->pTable->aCol[iColumn].affinity;
        if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;

        /* Figure out the collation sequence required from an index for
        ** it to be useful for optimising expression pX. Store this
        ** value in variable pColl.
        */
        assert(pX->pLeft);
        pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
        assert(pColl || pParse->nErr);

        for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
          if( NEVER(j>=pIdx->nColumn) ) return 0;
        }
        if( pColl && sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
      }
      return pTerm;

    }
  }
  return 0;
}

/* Forward reference */
static void exprAnalyze(SrcList*, WhereClause*, int);
................................................................................
  if( op==TK_VARIABLE ){
    Vdbe *pReprepare = pParse->pReprepare;
    int iCol = pRight->iColumn;
    pVal = sqlite3VdbeGetValue(pReprepare, iCol, SQLITE_AFF_NONE);
    if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
      z = (char *)sqlite3_value_text(pVal);
    }
    sqlite3VdbeSetVarmask(pParse->pVdbe, iCol); /* IMP: R-23257-02778 */
    assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
  }else if( op==TK_STRING ){
    z = pRight->u.zToken;
  }
  if( z ){
    cnt = 0;
    while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
................................................................................
      Expr *pPrefix;
      *pisComplete = c==wc[0] && z[cnt+1]==0;
      pPrefix = sqlite3Expr(db, TK_STRING, z);
      if( pPrefix ) pPrefix->u.zToken[cnt] = 0;
      *ppPrefix = pPrefix;
      if( op==TK_VARIABLE ){
        Vdbe *v = pParse->pVdbe;
        sqlite3VdbeSetVarmask(v, pRight->iColumn); /* IMP: R-23257-02778 */
        if( *pisComplete && pRight->u.zToken[1] ){
          /* If the rhs of the LIKE expression is a variable, and the current
          ** value of the variable means there is no need to invoke the LIKE
          ** function, then no OP_Variable will be added to the program.
          ** This causes problems for the sqlite3_bind_parameter_name()
          ** API. To workaround them, add a dummy OP_Variable here.
          */ 
................................................................................
  */
  assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
  assert( pExpr->op==TK_OR );
  pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
  if( pOrInfo==0 ) return;
  pTerm->wtFlags |= TERM_ORINFO;
  pOrWc = &pOrInfo->wc;
  whereClauseInit(pOrWc, pWC->pParse, pMaskSet);
  whereSplit(pOrWc, pExpr, TK_OR);
  exprAnalyzeAll(pSrc, pOrWc);
  if( db->mallocFailed ) return;
  assert( pOrWc->nTerm>=2 );

  /*
  ** Compute the set of tables that might satisfy cases 1 or 2.
................................................................................
        WhereTerm *pAndTerm;
        int j;
        Bitmask b = 0;
        pOrTerm->u.pAndInfo = pAndInfo;
        pOrTerm->wtFlags |= TERM_ANDINFO;
        pOrTerm->eOperator = WO_AND;
        pAndWC = &pAndInfo->wc;
        whereClauseInit(pAndWC, pWC->pParse, pMaskSet);
        whereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
        exprAnalyzeAll(pSrc, pAndWC);

        testcase( db->mallocFailed );
        if( !db->mallocFailed ){
          for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
            assert( pAndTerm->pExpr );
            if( allowedOp(pAndTerm->pExpr->op) ){
              b |= getMask(pMaskSet, pAndTerm->leftCursor);
            }
................................................................................
      pTerm->nChild = 1;
      pTerm->wtFlags |= TERM_COPIED;
      pNewTerm->prereqAll = pTerm->prereqAll;
    }
  }
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifdef SQLITE_ENABLE_STAT2
  /* When sqlite_stat2 histogram data is available an operator of the
  ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
  ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
  ** virtual term of that form.
  **
  ** Note that the virtual term must be tagged with TERM_VNULL.  This
  ** TERM_VNULL tag will suppress the not-null check at the beginning
  ** of the loop.  Without the TERM_VNULL flag, the not-null check at
................................................................................
      pNewTerm->iParent = idxTerm;
      pTerm = &pWC->a[idxTerm];
      pTerm->nChild = 1;
      pTerm->wtFlags |= TERM_COPIED;
      pNewTerm->prereqAll = pTerm->prereqAll;
    }
  }
#endif /* SQLITE_ENABLE_STAT2 */

  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}

................................................................................
){
#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  const int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur);  /* Bitmask for pSrc */
  WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm];        /* End of pWC->a[] */
  WhereTerm *pTerm;                 /* A single term of the WHERE clause */

  /* No OR-clause optimization allowed if the INDEXED BY or NOT INDEXED clauses
  ** are used */
  if( pSrc->notIndexed || pSrc->pIndex!=0 ){
    return;



  }

  /* Search the WHERE clause terms for a usable WO_OR term. */
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( pTerm->eOperator==WO_OR 
     && ((pTerm->prereqAll & ~maskSrc) & notReady)==0
     && (pTerm->u.pOrInfo->indexable & maskSrc)!=0 
................................................................................
        if( pOrTerm->eOperator==WO_AND ){
          WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc;
          bestIndex(pParse, pAndWC, pSrc, notReady, notValid, 0, &sTermCost);
        }else if( pOrTerm->leftCursor==iCur ){
          WhereClause tempWC;
          tempWC.pParse = pWC->pParse;
          tempWC.pMaskSet = pWC->pMaskSet;

          tempWC.op = TK_AND;
          tempWC.a = pOrTerm;

          tempWC.nTerm = 1;
          bestIndex(pParse, &tempWC, pSrc, notReady, notValid, 0, &sTermCost);
        }else{
          continue;
        }
        rTotal += sTermCost.rCost;
        nRow += sTermCost.plan.nRow;
................................................................................
  /* Try to find a more efficient access pattern by using multiple indexes
  ** to optimize an OR expression within the WHERE clause. 
  */
  bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost);
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */


/*
** Argument pIdx is a pointer to an index structure that has an array of
** SQLITE_INDEX_SAMPLES evenly spaced samples of the first indexed column
** stored in Index.aSample. These samples divide the domain of values stored
** the index into (SQLITE_INDEX_SAMPLES+1) regions.
** Region 0 contains all values less than the first sample value. Region
** 1 contains values between the first and second samples.  Region 2 contains
** values between samples 2 and 3.  And so on.  Region SQLITE_INDEX_SAMPLES
** contains values larger than the last sample.
**
** If the index contains many duplicates of a single value, then it is
** possible that two or more adjacent samples can hold the same value.
** When that is the case, the smallest possible region code is returned
** when roundUp is false and the largest possible region code is returned
** when roundUp is true.


**
** If successful, this function determines which of the regions value 
** pVal lies in, sets *piRegion to the region index (a value between 0
** and SQLITE_INDEX_SAMPLES+1, inclusive) and returns SQLITE_OK.
** Or, if an OOM occurs while converting text values between encodings,
** SQLITE_NOMEM is returned and *piRegion is undefined.

*/
#ifdef SQLITE_ENABLE_STAT2
static int whereRangeRegion(
  Parse *pParse,              /* Database connection */
  Index *pIdx,                /* Index to consider domain of */
  sqlite3_value *pVal,        /* Value to consider */
  int roundUp,                /* Return largest valid region if true */
  int *piRegion               /* OUT: Region of domain in which value lies */
){







  assert( roundUp==0 || roundUp==1 );
  if( ALWAYS(pVal) ){



    IndexSample *aSample = pIdx->aSample;
    int i = 0;
    int eType = sqlite3_value_type(pVal);

    if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){



















      double r = sqlite3_value_double(pVal);
      for(i=0; i<SQLITE_INDEX_SAMPLES; i++){

        if( aSample[i].eType==SQLITE_NULL ) continue;
        if( aSample[i].eType>=SQLITE_TEXT ) break;
        if( roundUp ){

          if( aSample[i].u.r>r ) break;
        }else{
          if( aSample[i].u.r>=r ) break;
        }



      }

    }else if( eType==SQLITE_NULL ){
      i = 0;
      if( roundUp ){
        while( i<SQLITE_INDEX_SAMPLES && aSample[i].eType==SQLITE_NULL ) i++;
      }
    }else{ 







      sqlite3 *db = pParse->db;
      CollSeq *pColl;
      const u8 *z;
      int n;

      /* pVal comes from sqlite3ValueFromExpr() so the type cannot be NULL */
      assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );

      if( eType==SQLITE_BLOB ){
        z = (const u8 *)sqlite3_value_blob(pVal);
        pColl = db->pDfltColl;
        assert( pColl->enc==SQLITE_UTF8 );
      }else{
        pColl = sqlite3GetCollSeq(db, SQLITE_UTF8, 0, *pIdx->azColl);
        if( pColl==0 ){
................................................................................
        z = (const u8 *)sqlite3ValueText(pVal, pColl->enc);
        if( !z ){
          return SQLITE_NOMEM;
        }
        assert( z && pColl && pColl->xCmp );
      }
      n = sqlite3ValueBytes(pVal, pColl->enc);

      for(i=0; i<SQLITE_INDEX_SAMPLES; i++){
        int c;
        int eSampletype = aSample[i].eType;
        if( eSampletype==SQLITE_NULL || eSampletype<eType ) continue;
        if( (eSampletype!=eType) ) break;
#ifndef SQLITE_OMIT_UTF16
        if( pColl->enc!=SQLITE_UTF8 ){
          int nSample;
          char *zSample = sqlite3Utf8to16(
              db, pColl->enc, aSample[i].u.z, aSample[i].nByte, &nSample
          );
          if( !zSample ){
................................................................................
          c = pColl->xCmp(pColl->pUser, nSample, zSample, n, z);
          sqlite3DbFree(db, zSample);
        }else
#endif
        {
          c = pColl->xCmp(pColl->pUser, aSample[i].nByte, aSample[i].u.z, n, z);
        }


        if( c-roundUp>=0 ) break;
      }
    }

    assert( i>=0 && i<=SQLITE_INDEX_SAMPLES );
    *piRegion = i;
  }































  return SQLITE_OK;
}
#endif   /* #ifdef SQLITE_ENABLE_STAT2 */

/*
** If expression pExpr represents a literal value, set *pp to point to
** an sqlite3_value structure containing the same value, with affinity
** aff applied to it, before returning. It is the responsibility of the 
** caller to eventually release this structure by passing it to 
** sqlite3ValueFree().
................................................................................
** create an sqlite3_value structure containing this value, again with
** affinity aff applied to it, instead.
**
** If neither of the above apply, set *pp to NULL.
**
** If an error occurs, return an error code. Otherwise, SQLITE_OK.
*/
#ifdef SQLITE_ENABLE_STAT2
static int valueFromExpr(
  Parse *pParse, 
  Expr *pExpr, 
  u8 aff, 
  sqlite3_value **pp
){
  if( pExpr->op==TK_VARIABLE
   || (pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE)
  ){
    int iVar = pExpr->iColumn;
    sqlite3VdbeSetVarmask(pParse->pVdbe, iVar); /* IMP: R-23257-02778 */
    *pp = sqlite3VdbeGetValue(pParse->pReprepare, iVar, aff);
    return SQLITE_OK;
  }
  return sqlite3ValueFromExpr(pParse->db, pExpr, SQLITE_UTF8, aff, pp);
}
#endif

................................................................................
** then nEq should be passed the value 1 (as the range restricted column,
** b, is the second left-most column of the index). Or, if the query is:
**
**   ... FROM t1 WHERE a > ? AND a < ? ...
**
** then nEq should be passed 0.
**
** The returned value is an integer between 1 and 100, inclusive. A return
** value of 1 indicates that the proposed range scan is expected to visit
** approximately 1/100th (1%) of the rows selected by the nEq equality
** constraints (if any). A return value of 100 indicates that it is expected
** that the range scan will visit every row (100%) selected by the equality
** constraints.
**
** In the absence of sqlite_stat2 ANALYZE data, each range inequality
** reduces the search space by 3/4ths.  Hence a single constraint (x>?)
** results in a return of 25 and a range constraint (x>? AND x<?) results
** in a return of 6.
*/
static int whereRangeScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index containing the range-compared column; "x" */
  int nEq,             /* index into p->aCol[] of the range-compared column */
  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
  int *piEst           /* OUT: Return value */
){
  int rc = SQLITE_OK;

#ifdef SQLITE_ENABLE_STAT2

  if( nEq==0 && p->aSample ){
    sqlite3_value *pLowerVal = 0;
    sqlite3_value *pUpperVal = 0;
    int iEst;
    int iLower = 0;
    int iUpper = SQLITE_INDEX_SAMPLES;
    int roundUpUpper = 0;
    int roundUpLower = 0;

    u8 aff = p->pTable->aCol[p->aiColumn[0]].affinity;

    if( pLower ){
      Expr *pExpr = pLower->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pLowerVal);
      assert( pLower->eOperator==WO_GT || pLower->eOperator==WO_GE );




      roundUpLower = (pLower->eOperator==WO_GT) ?1:0;


    }
    if( rc==SQLITE_OK && pUpper ){
      Expr *pExpr = pUpper->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pUpperVal);
      assert( pUpper->eOperator==WO_LT || pUpper->eOperator==WO_LE );




      roundUpUpper = (pUpper->eOperator==WO_LE) ?1:0;
    }


    if( rc!=SQLITE_OK || (pLowerVal==0 && pUpperVal==0) ){
      sqlite3ValueFree(pLowerVal);
      sqlite3ValueFree(pUpperVal);
      goto range_est_fallback;
    }else if( pLowerVal==0 ){
      rc = whereRangeRegion(pParse, p, pUpperVal, roundUpUpper, &iUpper);
      if( pLower ) iLower = iUpper/2;
    }else if( pUpperVal==0 ){
      rc = whereRangeRegion(pParse, p, pLowerVal, roundUpLower, &iLower);
      if( pUpper ) iUpper = (iLower + SQLITE_INDEX_SAMPLES + 1)/2;
    }else{
      rc = whereRangeRegion(pParse, p, pUpperVal, roundUpUpper, &iUpper);
      if( rc==SQLITE_OK ){
        rc = whereRangeRegion(pParse, p, pLowerVal, roundUpLower, &iLower);

      }
    }
    WHERETRACE(("range scan regions: %d..%d\n", iLower, iUpper));



    iEst = iUpper - iLower;
    testcase( iEst==SQLITE_INDEX_SAMPLES );
    assert( iEst<=SQLITE_INDEX_SAMPLES );
    if( iEst<1 ){
      *piEst = 50/SQLITE_INDEX_SAMPLES;
    }else{
      *piEst = (iEst*100)/SQLITE_INDEX_SAMPLES;
    }
    sqlite3ValueFree(pLowerVal);
    sqlite3ValueFree(pUpperVal);
    return rc;
  }
range_est_fallback:
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(p);
  UNUSED_PARAMETER(nEq);
#endif
  assert( pLower || pUpper );
  *piEst = 100;

  if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ) *piEst /= 4;
  if( pUpper ) *piEst /= 4;
  return rc;
}

#ifdef SQLITE_ENABLE_STAT2
/*
** Estimate the number of rows that will be returned based on
** an equality constraint x=VALUE and where that VALUE occurs in
** the histogram data.  This only works when x is the left-most
** column of an index and sqlite_stat2 histogram data is available
** for that index.  When pExpr==NULL that means the constraint is
** "x IS NULL" instead of "x=VALUE".
**
** Write the estimated row count into *pnRow and return SQLITE_OK. 
** If unable to make an estimate, leave *pnRow unchanged and return
** non-zero.
**
................................................................................
static int whereEqualScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index whose left-most column is pTerm */
  Expr *pExpr,         /* Expression for VALUE in the x=VALUE constraint */
  double *pnRow        /* Write the revised row estimate here */
){
  sqlite3_value *pRhs = 0;  /* VALUE on right-hand side of pTerm */
  int iLower, iUpper;       /* Range of histogram regions containing pRhs */
  u8 aff;                   /* Column affinity */
  int rc;                   /* Subfunction return code */
  double nRowEst;           /* New estimate of the number of rows */


  assert( p->aSample!=0 );

  aff = p->pTable->aCol[p->aiColumn[0]].affinity;
  if( pExpr ){
    rc = valueFromExpr(pParse, pExpr, aff, &pRhs);
    if( rc ) goto whereEqualScanEst_cancel;
  }else{
    pRhs = sqlite3ValueNew(pParse->db);
  }
  if( pRhs==0 ) return SQLITE_NOTFOUND;
  rc = whereRangeRegion(pParse, p, pRhs, 0, &iLower);
  if( rc ) goto whereEqualScanEst_cancel;
  rc = whereRangeRegion(pParse, p, pRhs, 1, &iUpper);
  if( rc ) goto whereEqualScanEst_cancel;
  WHERETRACE(("equality scan regions: %d..%d\n", iLower, iUpper));
  if( iLower>=iUpper ){
    nRowEst = p->aiRowEst[0]/(SQLITE_INDEX_SAMPLES*2);
    if( nRowEst<*pnRow ) *pnRow = nRowEst;
  }else{
    nRowEst = (iUpper-iLower)*p->aiRowEst[0]/SQLITE_INDEX_SAMPLES;
    *pnRow = nRowEst;
  }

whereEqualScanEst_cancel:
  sqlite3ValueFree(pRhs);
  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT2) */

#ifdef SQLITE_ENABLE_STAT2
/*
** Estimate the number of rows that will be returned based on
** an IN constraint where the right-hand side of the IN operator
** is a list of values.  Example:
**
**        WHERE x IN (1,2,3,4)
**
................................................................................
*/
static int whereInScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index whose left-most column is pTerm */
  ExprList *pList,     /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
  double *pnRow        /* Write the revised row estimate here */
){
  sqlite3_value *pVal = 0;  /* One value from list */
  int iLower, iUpper;       /* Range of histogram regions containing pRhs */
  u8 aff;                   /* Column affinity */
  int rc = SQLITE_OK;       /* Subfunction return code */

  double nRowEst;           /* New estimate of the number of rows */
  int nSpan = 0;            /* Number of histogram regions spanned */
  int nSingle = 0;          /* Histogram regions hit by a single value */
  int nNotFound = 0;        /* Count of values that are not constants */
  int i;                               /* Loop counter */
  u8 aSpan[SQLITE_INDEX_SAMPLES+1];    /* Histogram regions that are spanned */
  u8 aSingle[SQLITE_INDEX_SAMPLES+1];  /* Histogram regions hit once */

  assert( p->aSample!=0 );
  aff = p->pTable->aCol[p->aiColumn[0]].affinity;
  memset(aSpan, 0, sizeof(aSpan));
  memset(aSingle, 0, sizeof(aSingle));
  for(i=0; i<pList->nExpr; i++){
    sqlite3ValueFree(pVal);
    rc = valueFromExpr(pParse, pList->a[i].pExpr, aff, &pVal);
    if( rc ) break;
    if( pVal==0 || sqlite3_value_type(pVal)==SQLITE_NULL ){
      nNotFound++;
      continue;



    }
    rc = whereRangeRegion(pParse, p, pVal, 0, &iLower);
    if( rc ) break;
    rc = whereRangeRegion(pParse, p, pVal, 1, &iUpper);
    if( rc ) break;
    if( iLower>=iUpper ){
      aSingle[iLower] = 1;
    }else{
      assert( iLower>=0 && iUpper<=SQLITE_INDEX_SAMPLES );
      while( iLower<iUpper ) aSpan[iLower++] = 1;
    }
  }
  if( rc==SQLITE_OK ){
    for(i=nSpan=0; i<=SQLITE_INDEX_SAMPLES; i++){
      if( aSpan[i] ){
        nSpan++;
      }else if( aSingle[i] ){
        nSingle++;
      }
    }
    nRowEst = (nSpan*2+nSingle)*p->aiRowEst[0]/(2*SQLITE_INDEX_SAMPLES)
               + nNotFound*p->aiRowEst[1];
    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];
    *pnRow = nRowEst;
    WHERETRACE(("IN row estimate: nSpan=%d, nSingle=%d, nNotFound=%d, est=%g\n",
                 nSpan, nSingle, nNotFound, nRowEst));
  }
  sqlite3ValueFree(pVal);
  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT2) */


/*
** Find the best query plan for accessing a particular table.  Write the
** best query plan and its cost into the WhereCost object supplied as the
** last parameter.
**
................................................................................
){
  int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  Index *pProbe;              /* An index we are evaluating */
  Index *pIdx;                /* Copy of pProbe, or zero for IPK index */
  int eqTermMask;             /* Current mask of valid equality operators */
  int idxEqTermMask;          /* Index mask of valid equality operators */
  Index sPk;                  /* A fake index object for the primary key */
  unsigned int aiRowEstPk[2]; /* The aiRowEst[] value for the sPk index */
  int aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
  int wsFlagMask;             /* Allowed flags in pCost->plan.wsFlag */

  /* Initialize the cost to a worst-case value */
  memset(pCost, 0, sizeof(*pCost));
  pCost->rCost = SQLITE_BIG_DBL;

................................................................................
    eqTermMask = WO_EQ|WO_IN;
    pIdx = 0;
  }

  /* Loop over all indices looking for the best one to use
  */
  for(; pProbe; pIdx=pProbe=pProbe->pNext){
    const unsigned int * const aiRowEst = pProbe->aiRowEst;
    double cost;                /* Cost of using pProbe */
    double nRow;                /* Estimated number of rows in result set */
    double log10N;              /* base-10 logarithm of nRow (inexact) */
    int rev;                    /* True to scan in reverse order */
    int wsFlags = 0;
    Bitmask used = 0;

    /* The following variables are populated based on the properties of
    ** index being evaluated. They are then used to determine the expected
    ** cost and number of rows returned.
................................................................................
    **
    **  bInEst:  
    **    Set to true if there was at least one "x IN (SELECT ...)" term used 
    **    in determining the value of nInMul.  Note that the RHS of the
    **    IN operator must be a SELECT, not a value list, for this variable
    **    to be true.
    **
    **  estBound:
    **    An estimate on the amount of the table that must be searched.  A
    **    value of 100 means the entire table is searched.  Range constraints
    **    might reduce this to a value less than 100 to indicate that only
    **    a fraction of the table needs searching.  In the absence of
    **    sqlite_stat2 ANALYZE data, a single inequality reduces the search
    **    space to 1/4rd its original size.  So an x>? constraint reduces
    **    estBound to 25.  Two constraints (x>? AND x<?) reduce estBound to 6.


    **
    **  bSort:   
    **    Boolean. True if there is an ORDER BY clause that will require an 
    **    external sort (i.e. scanning the index being evaluated will not 
    **    correctly order records).
    **
    **  bLookup: 
................................................................................
    **
    **             SELECT a, b    FROM tbl WHERE a = 1;
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;                      /* Number of == or IN terms matching index */
    int bInEst = 0;               /* True if "x IN (SELECT...)" seen */
    int nInMul = 1;               /* Number of distinct equalities to lookup */
    int estBound = 100;           /* Estimated reduction in search space */
    int nBound = 0;               /* Number of range constraints seen */
    int bSort = !!pOrderBy;       /* True if external sort required */
    int bDist = !!pDistinct;      /* True if index cannot help with DISTINCT */
    int bLookup = 0;              /* True if not a covering index */
    WhereTerm *pTerm;             /* A single term of the WHERE clause */
#ifdef SQLITE_ENABLE_STAT2
    WhereTerm *pFirstTerm = 0;    /* First term matching the index */
#endif

    /* Determine the values of nEq and nInMul */
    for(nEq=0; nEq<pProbe->nColumn; nEq++){
      int j = pProbe->aiColumn[nEq];
      pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pIdx);
      if( pTerm==0 ) break;
      wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);

      if( pTerm->eOperator & WO_IN ){
        Expr *pExpr = pTerm->pExpr;
        wsFlags |= WHERE_COLUMN_IN;
        if( ExprHasProperty(pExpr, EP_xIsSelect) ){
          /* "x IN (SELECT ...)":  Assume the SELECT returns 25 rows */
          nInMul *= 25;
          bInEst = 1;
................................................................................
        }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
          /* "x IN (value, value, ...)" */
          nInMul *= pExpr->x.pList->nExpr;
        }
      }else if( pTerm->eOperator & WO_ISNULL ){
        wsFlags |= WHERE_COLUMN_NULL;
      }
#ifdef SQLITE_ENABLE_STAT2
      if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
      used |= pTerm->prereqRight;
    }

    /* Determine the value of estBound. */
    if( nEq<pProbe->nColumn && pProbe->bUnordered==0 ){
      int j = pProbe->aiColumn[nEq];
      if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
        WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx);
        WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx);
        whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &estBound);
        if( pTop ){
          nBound = 1;
          wsFlags |= WHERE_TOP_LIMIT;
          used |= pTop->prereqRight;

        }
        if( pBtm ){
          nBound++;
          wsFlags |= WHERE_BTM_LIMIT;
          used |= pBtm->prereqRight;

        }
        wsFlags |= (WHERE_COLUMN_RANGE|WHERE_ROWID_RANGE);
      }
    }else if( pProbe->onError!=OE_None ){
      testcase( wsFlags & WHERE_COLUMN_IN );
      testcase( wsFlags & WHERE_COLUMN_NULL );
      if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
................................................................................
    */
    nRow = (double)(aiRowEst[nEq] * nInMul);
    if( bInEst && nRow*2>aiRowEst[0] ){
      nRow = aiRowEst[0]/2;
      nInMul = (int)(nRow / aiRowEst[nEq]);
    }

#ifdef SQLITE_ENABLE_STAT2
    /* If the constraint is of the form x=VALUE or x IN (E1,E2,...)
    ** and we do not think that values of x are unique and if histogram
    ** data is available for column x, then it might be possible
    ** to get a better estimate on the number of rows based on
    ** VALUE and how common that value is according to the histogram.
    */
    if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 && aiRowEst[1]>1 ){

      if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){
        testcase( pFirstTerm->eOperator==WO_EQ );
        testcase( pFirstTerm->eOperator==WO_ISNULL );
        whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow);

      }else if( pFirstTerm->eOperator==WO_IN && bInEst==0 ){
        whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow);
      }
    }
#endif /* SQLITE_ENABLE_STAT2 */

    /* Adjust the number of output rows and downward to reflect rows
    ** that are excluded by range constraints.
    */
    nRow = (nRow * (double)estBound) / (double)100;
    if( nRow<1 ) nRow = 1;

    /* Experiments run on real SQLite databases show that the time needed
    ** to do a binary search to locate a row in a table or index is roughly
    ** log10(N) times the time to move from one row to the next row within
    ** a table or index.  The actual times can vary, with the size of
    ** records being an important factor.  Both moves and searches are
    ** slower with larger records, presumably because fewer records fit
    ** on one page and hence more pages have to be fetched.
    **
    ** The ANALYZE command and the sqlite_stat1 and sqlite_stat2 tables do
    ** not give us data on the relative sizes of table and index records.
    ** So this computation assumes table records are about twice as big
    ** as index records
    */
    if( (wsFlags & WHERE_NOT_FULLSCAN)==0 ){
      /* The cost of a full table scan is a number of move operations equal
      ** to the number of rows in the table.
................................................................................
        }
      }
      if( nRow<2 ) nRow = 2;
    }


    WHERETRACE((
      "%s(%s): nEq=%d nInMul=%d estBound=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
      "         notReady=0x%llx log10N=%.1f nRow=%.1f cost=%.1f used=0x%llx\n",
      pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), 
      nEq, nInMul, estBound, bSort, bLookup, wsFlags,
      notReady, log10N, nRow, cost, used
    ));

    /* If this index is the best we have seen so far, then record this
    ** index and its cost in the pCost structure.
    */
    if( (!pIdx || wsFlags)
................................................................................
** Generate code for the start of the iLevel-th loop in the WHERE clause
** implementation described by pWInfo.
*/
static Bitmask codeOneLoopStart(
  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
  int iLevel,          /* Which level of pWInfo->a[] should be coded */
  u16 wctrlFlags,      /* One of the WHERE_* flags defined in sqliteInt.h */
  Bitmask notReady     /* Which tables are currently available */

){
  int j, k;            /* Loop counters */
  int iCur;            /* The VDBE cursor for the table */
  int addrNxt;         /* Where to jump to continue with the next IN case */
  int omitTable;       /* True if we use the index only */
  int bRev;            /* True if we need to scan in reverse order */
  WhereLevel *pLevel;  /* The where level to be coded */
................................................................................

    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
    int regRowset = 0;                        /* Register for RowSet object */
    int regRowid = 0;                         /* Register holding rowid */
    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
    int iRetInit;                             /* Address of regReturn init */
    int untestedTerms = 0;             /* Some terms not completely tested */
    int ii;

   
    pTerm = pLevel->plan.u.pTerm;
    assert( pTerm!=0 );
    assert( pTerm->eOperator==WO_OR );
    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
    pOrWc = &pTerm->u.pOrInfo->wc;
    pLevel->op = OP_Return;
................................................................................
    */
    if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
      regRowset = ++pParse->nMem;
      regRowid = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
    }
    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);











    for(ii=0; ii<pOrWc->nTerm; ii++){
      WhereTerm *pOrTerm = &pOrWc->a[ii];
      if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){
        WhereInfo *pSubWInfo;          /* Info for single OR-term scan */





        /* Loop through table entries that match term pOrTerm. */
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrTerm->pExpr, 0, 0,
                        WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE |
                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY);
        if( pSubWInfo ){
          explainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
................................................................................
          if( pSubWInfo->untestedTerms ) untestedTerms = 1;

          /* Finish the loop through table entries that match term pOrTerm. */
          sqlite3WhereEnd(pSubWInfo);
        }
      }
    }

    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
    sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
    sqlite3VdbeResolveLabel(v, iLoopBody);

    if( pWInfo->nLevel>1 ) sqlite3StackFree(pParse->db, pOrTab);
    if( !untestedTerms ) disableTerm(pLevel, pTerm);
  }else
................................................................................
  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
  if( db->flags & SQLITE_DistinctOpt ) pDistinct = 0;

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(pWC, pParse, pMaskSet);
  sqlite3ExprCodeConstants(pParse, pWhere);
  whereSplit(pWC, pWhere, TK_AND);   /* IMP: R-15842-53296 */
    
  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  if( pWhere && (nTabList==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
................................................................................
      }
    }
    assert( bestJ>=0 );
    assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
    WHERETRACE(("*** Optimizer selects table %d for loop %d"
                " with cost=%g and nRow=%g\n",
                bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow));

    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
      *ppOrderBy = 0;
    }
    if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){
      assert( pWInfo->eDistinct==0 );
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }
    andFlags &= bestPlan.plan.wsFlags;
................................................................................
    if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){
      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
      int iCur = pTabItem->iCursor;
      sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB);
    }else
#endif
    if( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0
         && (wctrlFlags & WHERE_OMIT_OPEN)==0 ){
      int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
      sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
      testcase( pTab->nCol==BMS-1 );
      testcase( pTab->nCol==BMS );
      if( !pWInfo->okOnePass && pTab->nCol<BMS ){
        Bitmask b = pTabItem->colUsed;
        int n = 0;
................................................................................
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(i=0; i<nTabList; i++){
    pLevel = &pWInfo->a[i];
    explainOneScan(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags);
    notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady);
    pWInfo->iContinue = pLevel->addrCont;
  }

#ifdef SQLITE_TEST  /* For testing and debugging use only */
  /* Record in the query plan information about the current table
  ** and the index used to access it (if any).  If the table itself
  ** is not used, its name is just '{}'.  If no index is used
................................................................................
  assert( pWInfo->nLevel==1 || pWInfo->nLevel==pTabList->nSrc );
  for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
    struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
    Table *pTab = pTabItem->pTab;
    assert( pTab!=0 );
    if( (pTab->tabFlags & TF_Ephemeral)==0
     && pTab->pSelect==0
     && (pWInfo->wctrlFlags & WHERE_OMIT_CLOSE)==0
    ){
      int ws = pLevel->plan.wsFlags;
      if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
        sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
      }
      if( (ws & WHERE_INDEXED)!=0 && (ws & WHERE_TEMP_INDEX)==0 ){
        sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
................................................................................
  void *yyp,                   /* The parser */
  int yymajor,                 /* The major token code number */
  sqlite3ParserTOKENTYPE yyminor       /* The value for the token */
  sqlite3ParserARG_PDECL               /* Optional %extra_argument parameter */
){
  YYMINORTYPE yyminorunion;
  int yyact;            /* The parser action. */

  int yyendofinput;     /* True if we are at the end of input */

#ifdef YYERRORSYMBOL
  int yyerrorhit = 0;   /* True if yymajor has invoked an error */
#endif
  yyParser *yypParser;  /* The parser */

  /* (re)initialize the parser, if necessary */
  yypParser = (yyParser*)yyp;
................................................................................
#endif
    yypParser->yyidx = 0;
    yypParser->yyerrcnt = -1;
    yypParser->yystack[0].stateno = 0;
    yypParser->yystack[0].major = 0;
  }
  yyminorunion.yy0 = yyminor;

  yyendofinput = (yymajor==0);

  sqlite3ParserARG_STORE;

#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sInput %s\n",yyTracePrompt,yyTokenName[yymajor]);
  }
#endif

  do{
    yyact = yy_find_shift_action(yypParser,(YYCODETYPE)yymajor);
    if( yyact<YYNSTATE ){
      assert( !yyendofinput );  /* Impossible to shift the $ token */
      yy_shift(yypParser,yyact,yymajor,&yyminorunion);
      yypParser->yyerrcnt--;
      yymajor = YYNOCODE;
    }else if( yyact < YYNSTATE + YYNRULE ){
      yy_reduce(yypParser,yyact-YYNSTATE);
    }else{
      assert( yyact == YY_ERROR_ACTION );
................................................................................
**    *  Calls to this routine from Y must block until the outer-most
**       call by X completes.
**
**    *  Recursive calls to this routine from thread X return immediately
**       without blocking.
*/
SQLITE_API int sqlite3_initialize(void){
  sqlite3_mutex *pMaster;                      /* The main static mutex */
  int rc;                                      /* Result code */

#ifdef SQLITE_OMIT_WSD
  rc = sqlite3_wsd_init(4096, 24);
  if( rc!=SQLITE_OK ){
    return rc;
  }
................................................................................

  /* Initialize the malloc() system and the recursive pInitMutex mutex.
  ** This operation is protected by the STATIC_MASTER mutex.  Note that
  ** MutexAlloc() is called for a static mutex prior to initializing the
  ** malloc subsystem - this implies that the allocation of a static
  ** mutex must not require support from the malloc subsystem.
  */
  pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(pMaster);
  sqlite3GlobalConfig.isMutexInit = 1;
  if( !sqlite3GlobalConfig.isMallocInit ){
    rc = sqlite3MallocInit();
  }
  if( rc==SQLITE_OK ){
    sqlite3GlobalConfig.isMallocInit = 1;
................................................................................
*/
SQLITE_API int sqlite3_overload_function(
  sqlite3 *db,
  const char *zName,
  int nArg
){
  int nName = sqlite3Strlen30(zName);
  int rc;
  sqlite3_mutex_enter(db->mutex);
  if( sqlite3FindFunction(db, zName, nName, nArg, SQLITE_UTF8, 0)==0 ){
    sqlite3CreateFunc(db, zName, nArg, SQLITE_UTF8,
                      0, sqlite3InvalidFunction, 0, 0, 0);
  }
  rc = sqlite3ApiExit(db, SQLITE_OK);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

#ifndef SQLITE_OMIT_TRACE
/*
** Register a trace function.  The pArg from the previously registered trace
................................................................................
opendb_out:
  sqlite3_free(zOpen);
  if( db ){
    assert( db->mutex!=0 || isThreadsafe==0 || sqlite3GlobalConfig.bFullMutex==0 );
    sqlite3_mutex_leave(db->mutex);
  }
  rc = sqlite3_errcode(db);

  if( rc==SQLITE_NOMEM ){
    sqlite3_close(db);
    db = 0;
  }else if( rc!=SQLITE_OK ){
    db->magic = SQLITE_MAGIC_SICK;
  }
  *ppDb = db;
................................................................................
#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
# define TESTONLY(X)  X
#else
# define TESTONLY(X)
#endif

#endif /* SQLITE_AMALGAMATION */








typedef struct Fts3Table Fts3Table;
typedef struct Fts3Cursor Fts3Cursor;
typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;
typedef struct Fts3PhraseToken Fts3PhraseToken;

................................................................................
  sqlite3_vtab base;              /* Base class used by SQLite core */
  sqlite3 *db;                    /* The database connection */
  const char *zDb;                /* logical database name */
  const char *zName;              /* virtual table name */
  int nColumn;                    /* number of named columns in virtual table */
  char **azColumn;                /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */


  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[27];

  char *zReadExprlist;
................................................................................
    int nPrefix;                  /* Prefix length (0 for main terms index) */
    Fts3Hash hPending;            /* Pending terms table for this index */
  } *aIndex;
  int nMaxPendingData;            /* Max pending data before flush to disk */
  int nPendingData;               /* Current bytes of pending data */
  sqlite_int64 iPrevDocid;        /* Docid of most recently inserted document */

#if defined(SQLITE_DEBUG)
  /* State variables used for validating that the transaction control
  ** methods of the virtual table are called at appropriate times.  These
  ** values do not contribution to the FTS computation; they are used for
  ** verifying the SQLite core.
  */
  int inTransaction;     /* True after xBegin but before xCommit/xRollback */
  int mxSavepoint;       /* Largest valid xSavepoint integer */
................................................................................
** For a sequence of tokens contained in double-quotes (i.e. "one two three")
** nToken will be the number of tokens in the string.
*/
struct Fts3PhraseToken {
  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */


  /* Variables above this point are populated when the expression is
  ** parsed (by code in fts3_expr.c). Below this point the variables are
  ** used when evaluating the expression. */
  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
  Fts3MultiSegReader *pSegcsr;    /* Segment-reader for this token */
};
................................................................................

/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008
#define FTS3_SEGMENT_SCAN          0x00000010


/* Type passed as 4th argument to SegmentReaderIterate() */
struct Fts3SegFilter {
  const char *zTerm;
  int nTerm;
  int iCol;
  int flags;
................................................................................
/* fts3.c */
SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *, sqlite3_int64);
SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64);
SQLITE_PRIVATE void sqlite3Fts3Dequote(char *);
SQLITE_PRIVATE void sqlite3Fts3DoclistPrev(int,char*,int,char**,sqlite3_int64*,int*,u8*);

SQLITE_PRIVATE int sqlite3Fts3EvalPhraseStats(Fts3Cursor *, Fts3Expr *, u32 *);


/* fts3_tokenizer.c */
SQLITE_PRIVATE const char *sqlite3Fts3NextToken(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3InitHashTable(sqlite3 *, Fts3Hash *, const char *);
SQLITE_PRIVATE int sqlite3Fts3InitTokenizer(Fts3Hash *pHash, const char *, 
    sqlite3_tokenizer **, char **
);
................................................................................
SQLITE_PRIVATE void sqlite3Fts3Snippet(sqlite3_context *, Fts3Cursor *, const char *,
  const char *, const char *, int, int
);
SQLITE_PRIVATE void sqlite3Fts3Matchinfo(sqlite3_context *, Fts3Cursor *, const char *);

/* fts3_expr.c */
SQLITE_PRIVATE int sqlite3Fts3ExprParse(sqlite3_tokenizer *, 
  char **, int, int, const char *, int, Fts3Expr **
);
SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *);
#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
SQLITE_PRIVATE int sqlite3Fts3InitTerm(sqlite3 *db);
#endif

................................................................................
*/
static void fts3GetReverseVarint(
  char **pp, 
  char *pStart, 
  sqlite3_int64 *pVal
){
  sqlite3_int64 iVal;
  char *p = *pp;

  /* Pointer p now points at the first byte past the varint we are 
  ** interested in. So, unless the doclist is corrupt, the 0x80 bit is
  ** clear on character p[-1]. */
  for(p = (*pp)-2; p>=pStart && *p&0x80; p--);
  p++;
  *pp = p;
................................................................................
  /* Free any prepared statements held */
  for(i=0; i<SizeofArray(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }
  sqlite3_free(p->zSegmentsTbl);
  sqlite3_free(p->zReadExprlist);
  sqlite3_free(p->zWriteExprlist);


  /* Invoke the tokenizer destructor to free the tokenizer. */
  p->pTokenizer->pModule->xDestroy(p->pTokenizer);

  sqlite3_free(p);
  return SQLITE_OK;
}
................................................................................
  }
}

/*
** The xDestroy() virtual table method.
*/
static int fts3DestroyMethod(sqlite3_vtab *pVtab){
  int rc = SQLITE_OK;              /* Return code */
  Fts3Table *p = (Fts3Table *)pVtab;


  sqlite3 *db = p->db;

  /* Drop the shadow tables */

  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_content'", p->zDb, p->zName);

  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segments'", p->zDb,p->zName);
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segdir'", p->zDb, p->zName);
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_docsize'", p->zDb, p->zName);
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_stat'", p->zDb, p->zName);

  /* If everything has worked, invoke fts3DisconnectMethod() to free the
  ** memory associated with the Fts3Table structure and return SQLITE_OK.
  ** Otherwise, return an SQLite error code.
  */
  return (rc==SQLITE_OK ? fts3DisconnectMethod(pVtab) : rc);
}
................................................................................
** If the p->bHasDocsize boolean is true (indicating that this is an
** FTS4 table, not an FTS3 table) then also create the %_docsize and
** %_stat tables required by FTS4.
*/
static int fts3CreateTables(Fts3Table *p){
  int rc = SQLITE_OK;             /* Return code */
  int i;                          /* Iterator variable */
  char *zContentCols;             /* Columns of %_content table */
  sqlite3 *db = p->db;            /* The database connection */




  /* Create a list of user columns for the content table */
  zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
  for(i=0; zContentCols && i<p->nColumn; i++){
    char *z = p->azColumn[i];
    zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
  }
  if( zContentCols==0 ) rc = SQLITE_NOMEM;

  /* Create the content table */
  fts3DbExec(&rc, db, 
     "CREATE TABLE %Q.'%q_content'(%s)",
     p->zDb, p->zName, zContentCols
  );
  sqlite3_free(zContentCols);


  /* Create other tables */
  fts3DbExec(&rc, db, 
      "CREATE TABLE %Q.'%q_segments'(blockid INTEGER PRIMARY KEY, block BLOB);",
      p->zDb, p->zName
  );
  fts3DbExec(&rc, db, 
      "CREATE TABLE %Q.'%q_segdir'("
................................................................................
    *(z++) = '"';
    *(z++) = '\0';
  }
  return zRet;
}

/*
** Return a list of comma separated SQL expressions that could be used
** in a SELECT statement such as the following:
**
**     SELECT <list of expressions> FROM %_content AS x ...
**
** to return the docid, followed by each column of text data in order
** from left to write. If parameter zFunc is not NULL, then instead of
** being returned directly each column of text data is passed to an SQL
** function named zFunc first. For example, if zFunc is "unzip" and the
** table has the three user-defined columns "a", "b", and "c", the following
** string is returned:
**
**     "docid, unzip(x.'a'), unzip(x.'b'), unzip(x.'c')"
**
** The pointer returned points to a buffer allocated by sqlite3_malloc(). It
** is the responsibility of the caller to eventually free it.
**
** If *pRc is not SQLITE_OK when this function is called, it is a no-op (and
** a NULL pointer is returned). Otherwise, if an OOM error is encountered
** by this function, NULL is returned and *pRc is set to SQLITE_NOMEM. If
................................................................................
*/
static char *fts3ReadExprList(Fts3Table *p, const char *zFunc, int *pRc){
  char *zRet = 0;
  char *zFree = 0;
  char *zFunction;
  int i;


  if( !zFunc ){
    zFunction = "";
  }else{
    zFree = zFunction = fts3QuoteId(zFunc);
  }
  fts3Appendf(pRc, &zRet, "docid");
  for(i=0; i<p->nColumn; i++){
    fts3Appendf(pRc, &zRet, ",%s(x.'c%d%q')", zFunction, i, p->azColumn[i]);
  }
  sqlite3_free(zFree);











  return zRet;
}

/*
** Return a list of N comma separated question marks, where N is the number
** of columns in the %_content table (one for the docid plus one for each
** user-defined text column).
................................................................................
**
** If *pp does not being with a decimal digit SQLITE_ERROR is returned and
** the output value undefined. Otherwise SQLITE_OK is returned.
**
** This function is used when parsing the "prefix=" FTS4 parameter.
*/
static int fts3GobbleInt(const char **pp, int *pnOut){
  const char *p = *pp;            /* Iterator pointer */
  int nInt = 0;                   /* Output value */

  for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
    nInt = nInt * 10 + (p[0] - '0');
  }
  if( p==*pp ) return SQLITE_ERROR;
  *pnOut = nInt;
................................................................................
      aIndex[i].nPrefix = nPrefix;
      p++;
    }
  }

  return SQLITE_OK;
}






















































































/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
................................................................................

  /* The results of parsing supported FTS4 key=value options: */
  int bNoDocsize = 0;             /* True to omit %_docsize table */
  int bDescIdx = 0;               /* True to store descending indexes */
  char *zPrefix = 0;              /* Prefix parameter value (or NULL) */
  char *zCompress = 0;            /* compress=? parameter (or NULL) */
  char *zUncompress = 0;          /* uncompress=? parameter (or NULL) */


  assert( strlen(argv[0])==4 );
  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)
  );

  nDb = (int)strlen(argv[1]) + 1;
................................................................................
    }

    /* Check if it is an FTS4 special argument. */
    else if( isFts4 && fts3IsSpecialColumn(z, &nKey, &zVal) ){
      struct Fts4Option {
        const char *zOpt;
        int nOpt;
        char **pzVar;
      } aFts4Opt[] = {
        { "matchinfo",   9, 0 },            /* 0 -> MATCHINFO */
        { "prefix",      6, 0 },            /* 1 -> PREFIX */
        { "compress",    8, 0 },            /* 2 -> COMPRESS */
        { "uncompress", 10, 0 },            /* 3 -> UNCOMPRESS */
        { "order",       5, 0 }             /* 4 -> ORDER */
      };

      int iOpt;
      if( !zVal ){
        rc = SQLITE_NOMEM;
      }else{
        for(iOpt=0; iOpt<SizeofArray(aFts4Opt); iOpt++){
................................................................................
              sqlite3_free(zUncompress);
              zUncompress = zVal;
              zVal = 0;
              break;

            case 4:               /* ORDER */
              if( (strlen(zVal)!=3 || sqlite3_strnicmp(zVal, "asc", 3)) 
               && (strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "desc", 3)) 
              ){
                *pzErr = sqlite3_mprintf("unrecognized order: %s", zVal);
                rc = SQLITE_ERROR;
              }
              bDescIdx = (zVal[0]=='d' || zVal[0]=='D');
              break;







          }
        }
        sqlite3_free(zVal);
      }
    }

    /* Otherwise, the argument is a column name. */
    else {
      nString += (int)(strlen(z) + 1);
      aCol[nCol++] = z;
    }
  }




















  if( rc!=SQLITE_OK ) goto fts3_init_out;

  if( nCol==0 ){
    assert( nString==0 );
    aCol[0] = "content";
    nString = 8;
    nCol = 1;
................................................................................
  p->nPendingData = 0;
  p->azColumn = (char **)&p[1];
  p->pTokenizer = pTokenizer;
  p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
  p->bHasDocsize = (isFts4 && bNoDocsize==0);
  p->bHasStat = isFts4;
  p->bDescIdx = bDescIdx;


  TESTONLY( p->inTransaction = -1 );
  TESTONLY( p->mxSavepoint = -1 );

  p->aIndex = (struct Fts3Index *)&p->azColumn[nCol];
  memcpy(p->aIndex, aIndex, sizeof(struct Fts3Index) * nIndex);
  p->nIndex = nIndex;
  for(i=0; i<nIndex; i++){
................................................................................
  fts3DeclareVtab(&rc, p);

fts3_init_out:
  sqlite3_free(zPrefix);
  sqlite3_free(aIndex);
  sqlite3_free(zCompress);
  sqlite3_free(zUncompress);

  sqlite3_free((void *)aCol);
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else if( pTokenizer ){
      pTokenizer->pModule->xDestroy(pTokenizer);
    }
................................................................................
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_free(pCsr);
  return SQLITE_OK;
}


























/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){

  if( pCsr->isRequireSeek ){




    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
    pCsr->isRequireSeek = 0;
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      return SQLITE_OK;
    }else{
      int rc = sqlite3_reset(pCsr->pStmt);
      if( rc==SQLITE_OK ){
        /* If no row was found and no error has occured, then the %_content
        ** table is missing a row that is present in the full-text index.
        ** The data structures are corrupt.
        */
        rc = SQLITE_CORRUPT_VTAB;
      }
      pCsr->isEof = 1;





      if( pContext ){
        sqlite3_result_error_code(pContext, rc);
      }
      return rc;
    }
  }else{
    return SQLITE_OK;
  }
}

/*
** This function is used to process a single interior node when searching
** a b-tree for a term or term prefix. The node data is passed to this 
** function via the zNode/nNode parameters. The term to search for is
** passed in zTerm/nTerm.
................................................................................
  ** contents, or two zero bytes. Or, if the node is read from the %_segments
  ** table, then there are always 20 bytes of zeroed padding following the
  ** nNode bytes of content (see sqlite3Fts3ReadBlock() for details).
  */
  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  if( zCsr>zEnd ){
    return SQLITE_CORRUPT_VTAB;
  }
  
  while( zCsr<zEnd && (piFirst || piLast) ){
    int cmp;                      /* memcmp() result */
    int nSuffix;                  /* Size of term suffix */
    int nPrefix = 0;              /* Size of term prefix */
    int nBuffer;                  /* Total term size */
................................................................................
    if( !isFirstTerm ){
      zCsr += sqlite3Fts3GetVarint32(zCsr, &nPrefix);
    }
    isFirstTerm = 0;
    zCsr += sqlite3Fts3GetVarint32(zCsr, &nSuffix);
    
    if( nPrefix<0 || nSuffix<0 || &zCsr[nSuffix]>zEnd ){
      rc = SQLITE_CORRUPT_VTAB;
      goto finish_scan;
    }
    if( nPrefix+nSuffix>nAlloc ){
      char *zNew;
      nAlloc = (nPrefix+nSuffix) * 2;
      zNew = (char *)sqlite3_realloc(zBuffer, nAlloc);
      if( !zNew ){
        rc = SQLITE_NOMEM;
        goto finish_scan;
      }
      zBuffer = zNew;
    }

    memcpy(&zBuffer[nPrefix], zCsr, nSuffix);
    nBuffer = nPrefix + nSuffix;
    zCsr += nSuffix;

    /* Compare the term we are searching for with the term just loaded from
    ** the interior node. If the specified term is greater than or equal
    ** to the term from the interior node, then all terms on the sub-tree 
................................................................................
  char **pp,                      /* IN/OUT: Preallocated output buffer */
  int nToken,                     /* Maximum difference in token positions */
  int isSaveLeft,                 /* Save the left position */
  int isExact,                    /* If *pp1 is exactly nTokens before *pp2 */
  char **pp1,                     /* IN/OUT: Left input list */
  char **pp2                      /* IN/OUT: Right input list */
){
  char *p = (pp ? *pp : 0);
  char *p1 = *pp1;
  char *p2 = *pp2;
  int iCol1 = 0;
  int iCol2 = 0;

  /* Never set both isSaveLeft and isExact for the same invocation. */
  assert( isSaveLeft==0 || isExact==0 );

  assert( *p1!=0 && *p2!=0 );
  if( *p1==POS_COLUMN ){ 
    p1++;
    p1 += sqlite3Fts3GetVarint32(p1, &iCol1);
  }
  if( *p2==POS_COLUMN ){ 
    p2++;
    p2 += sqlite3Fts3GetVarint32(p2, &iCol2);
................................................................................
  while( 1 ){
    if( iCol1==iCol2 ){
      char *pSave = p;
      sqlite3_int64 iPrev = 0;
      sqlite3_int64 iPos1 = 0;
      sqlite3_int64 iPos2 = 0;

      if( pp && iCol1 ){
        *p++ = POS_COLUMN;
        p += sqlite3Fts3PutVarint(p, iCol1);
      }

      assert( *p1!=POS_END && *p1!=POS_COLUMN );
      assert( *p2!=POS_END && *p2!=POS_COLUMN );
      fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
................................................................................
      fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;

      while( 1 ){
        if( iPos2==iPos1+nToken 
         || (isExact==0 && iPos2>iPos1 && iPos2<=iPos1+nToken) 
        ){
          sqlite3_int64 iSave;
          if( !pp ){
            fts3PoslistCopy(0, &p2);
            fts3PoslistCopy(0, &p1);
            *pp1 = p1;
            *pp2 = p2;
            return 1;
          }
          iSave = isSaveLeft ? iPos1 : iPos2;
          fts3PutDeltaVarint(&p, &iPrev, iSave+2); iPrev -= 2;
          pSave = 0;

        }
        if( (!isSaveLeft && iPos2<=(iPos1+nToken)) || iPos2<=iPos1 ){
          if( (*p2&0xFE)==0 ) break;
          fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;
        }else{
          if( (*p1&0xFE)==0 ) break;
          fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
................................................................................
    }
  }

  fts3PoslistCopy(0, &p2);
  fts3PoslistCopy(0, &p1);
  *pp1 = p1;
  *pp2 = p2;
  if( !pp || *pp==p ){
    return 0;
  }
  *p++ = 0x00;
  *pp = p;
  return 1;
}

................................................................................
      fts3PoslistCopy(0, &p2);
      fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
    }
  }

  *pnRight = p - aOut;
}




















































/*
** Merge all doclists in the TermSelect.aaOutput[] array into a single
** doclist stored in TermSelect.aaOutput[0]. If successful, delete all
** other doclists (except the aaOutput[0] one) and return SQLITE_OK.
**
................................................................................
  Fts3SegFilter filter;           /* Segment term filter configuration */

  pSegcsr = pTok->pSegcsr;
  memset(&tsc, 0, sizeof(TermSelect));

  filter.flags = FTS3_SEGMENT_IGNORE_EMPTY | FTS3_SEGMENT_REQUIRE_POS
        | (pTok->isPrefix ? FTS3_SEGMENT_PREFIX : 0)

        | (iColumn<p->nColumn ? FTS3_SEGMENT_COLUMN_FILTER : 0);
  filter.iCol = iColumn;
  filter.zTerm = pTok->z;
  filter.nTerm = pTok->n;

  rc = sqlite3Fts3SegReaderStart(p, pSegcsr, &filter);
  while( SQLITE_OK==rc
................................................................................
    int iCol = idxNum-FTS3_FULLTEXT_SEARCH;
    const char *zQuery = (const char *)sqlite3_value_text(apVal[0]);

    if( zQuery==0 && sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
      return SQLITE_NOMEM;
    }

    rc = sqlite3Fts3ExprParse(p->pTokenizer, p->azColumn, p->nColumn, 
        iCol, zQuery, -1, &pCsr->pExpr
    );
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_ERROR ){
        static const char *zErr = "malformed MATCH expression: [%s]";
        p->base.zErrMsg = sqlite3_mprintf(zErr, zQuery);
      }
      return rc;
................................................................................

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  if( idxNum==FTS3_FULLSCAN_SEARCH ){


    const char *zSort = (pCsr->bDesc ? "DESC" : "ASC");
    const char *zTmpl = "SELECT %s FROM %Q.'%q_content' AS x ORDER BY docid %s";
    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist, p->zDb, p->zName, zSort);
  }else{

    const char *zTmpl = "SELECT %s FROM %Q.'%q_content' AS x WHERE docid = ?";
    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist, p->zDb, p->zName);
  }
  if( !zSql ) return SQLITE_NOMEM;
  rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
  sqlite3_free(zSql);
  if( rc!=SQLITE_OK ) return rc;



  if( idxNum==FTS3_DOCID_SEARCH ){


    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
    if( rc!=SQLITE_OK ) return rc;
  }



  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/
................................................................................
  }else if( iCol==p->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor.
    */
    sqlite3_result_blob(pContext, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);
  }else{
    rc = fts3CursorSeek(0, pCsr);
    if( rc==SQLITE_OK ){
      sqlite3_result_value(pContext, sqlite3_column_value(pCsr->pStmt, iCol+1));
    }
  }

  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  return rc;
}
................................................................................
** When called, *ppPoslist must point to the byte immediately following the
** end of a position-list. i.e. ( (*ppPoslist)[-1]==POS_END ). This function
** moves *ppPoslist so that it instead points to the first byte of the
** same position list.
*/
static void fts3ReversePoslist(char *pStart, char **ppPoslist){
  char *p = &(*ppPoslist)[-2];
  char c;

  while( p>pStart && (c=*p--)==0 );
  while( p>pStart && (*p & 0x80) | c ){ 
    c = *p--; 
  }
  if( p>pStart ){ p = &p[2]; }
  while( *p++&0x80 );
................................................................................
  sqlite3_vtab *pVtab,            /* Virtual table handle */
  const char *zName               /* New name of table */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  sqlite3 *db = p->db;            /* Database connection */
  int rc;                         /* Return Code */








  rc = sqlite3Fts3PendingTermsFlush(p);
  if( rc!=SQLITE_OK ){
    return rc;
  }


  fts3DbExec(&rc, db,
    "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';",
    p->zDb, p->zName, zName
  );


  if( p->bHasDocsize ){
    fts3DbExec(&rc, db,
      "ALTER TABLE %Q.'%q_docsize'  RENAME TO '%q_docsize';",
      p->zDb, p->zName, zName
    );
  }
  if( p->bHasStat ){
................................................................................
** means that the phrase does not appear in the current row, doclist.pList
** and doclist.nList are both zeroed.
**
** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
*/
static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
  int iToken;                     /* Used to iterate through phrase tokens */
  int rc = SQLITE_OK;             /* Return code */
  char *aPoslist = 0;             /* Position list for deferred tokens */
  int nPoslist = 0;               /* Number of bytes in aPoslist */
  int iPrev = -1;                 /* Token number of previous deferred token */

  assert( pPhrase->doclist.bFreeList==0 );

  for(iToken=0; rc==SQLITE_OK && iToken<pPhrase->nToken; iToken++){
    Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
    Fts3DeferredToken *pDeferred = pToken->pDeferred;

    if( pDeferred ){
      char *pList;
      int nList;
      rc = sqlite3Fts3DeferredTokenList(pDeferred, &pList, &nList);
      if( rc!=SQLITE_OK ) return rc;

      if( pList==0 ){
        sqlite3_free(aPoslist);
        pPhrase->doclist.pList = 0;
        pPhrase->doclist.nList = 0;
        return SQLITE_OK;
................................................................................
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;

  if( pCsr->bDesc==pTab->bDescIdx 
   && bOptOk==1 
   && p->nToken==1 
   && pFirst->pSegcsr 
   && pFirst->pSegcsr->bLookup 

  ){
    /* Use the incremental approach. */
    int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
    rc = sqlite3Fts3MsrIncrStart(
        pTab, pFirst->pSegcsr, iCol, pFirst->z, pFirst->n);
    p->bIncr = 1;

................................................................................
  Fts3Cursor *pCsr,               /* FTS Cursor handle */
  Fts3Expr *pRoot,                /* Root of current AND/NEAR cluster */
  Fts3Expr *pExpr,                /* Expression to consider */
  Fts3TokenAndCost **ppTC,        /* Write new entries to *(*ppTC)++ */
  Fts3Expr ***ppOr,               /* Write new OR root to *(*ppOr)++ */
  int *pRc                        /* IN/OUT: Error code */
){
  if( *pRc==SQLITE_OK && pExpr ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      for(i=0; *pRc==SQLITE_OK && i<pPhrase->nToken; i++){
        Fts3TokenAndCost *pTC = (*ppTC)++;
        pTC->pPhrase = pPhrase;
        pTC->iToken = i;
        pTC->pRoot = pRoot;
        pTC->pToken = &pPhrase->aToken[i];
        pTC->iCol = pPhrase->iColumn;
        *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
      }
    }else if( pExpr->eType!=FTSQUERY_NOT ){





      if( pExpr->eType==FTSQUERY_OR ){
        pRoot = pExpr->pLeft;
        **ppOr = pRoot;
        (*ppOr)++;
      }
      fts3EvalTokenCosts(pCsr, pRoot, pExpr->pLeft, ppTC, ppOr, pRc);
      if( pExpr->eType==FTSQUERY_OR ){
................................................................................
    pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
    a += sqlite3Fts3GetVarint(a, &nDoc);
    while( a<pEnd ){
      a += sqlite3Fts3GetVarint(a, &nByte);
    }
    if( nDoc==0 || nByte==0 ){
      sqlite3_reset(pStmt);
      return SQLITE_CORRUPT_VTAB;
    }

    pCsr->nDoc = nDoc;
    pCsr->nRowAvg = (int)(((nByte / nDoc) + p->nPgsz) / p->nPgsz);
    assert( pCsr->nRowAvg>0 ); 
    rc = sqlite3_reset(pStmt);
    if( rc!=SQLITE_OK ) return rc;
................................................................................
  int rc = SQLITE_OK;             /* Return code */
  int ii;                         /* Iterator variable for various purposes */
  int nOvfl = 0;                  /* Total overflow pages used by doclists */
  int nToken = 0;                 /* Total number of tokens in cluster */

  int nMinEst = 0;                /* The minimum count for any phrase so far. */
  int nLoad4 = 1;                 /* (Phrases that will be loaded)^4. */










  /* Count the tokens in this AND/NEAR cluster. If none of the doclists
  ** associated with the tokens spill onto overflow pages, or if there is
  ** only 1 token, exit early. No tokens to defer in this case. */
  for(ii=0; ii<nTC; ii++){
    if( aTC[ii].pRoot==pRoot ){
      nOvfl += aTC[ii].nOvfl;
................................................................................
      ** that will be loaded if all subsequent tokens are deferred.
      */
      Fts3PhraseToken *pToken = pTC->pToken;
      rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
      fts3SegReaderCursorFree(pToken->pSegcsr);
      pToken->pSegcsr = 0;
    }else{



      nLoad4 = nLoad4*4;

      if( ii==0 || pTC->pPhrase->nToken>1 ){
        /* Either this is the cheapest token in the entire query, or it is
        ** part of a multi-token phrase. Either way, the entire doclist will
        ** (eventually) be loaded into memory. It may as well be now. */
        Fts3PhraseToken *pToken = pTC->pToken;
        int nList = 0;
        char *pList = 0;
................................................................................
        int nNear = p->nNear;
        res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
      }
  
      aPoslist = pExpr->pRight->pPhrase->doclist.pList;
      nToken = pExpr->pRight->pPhrase->nToken;
      for(p=pExpr->pLeft; p && res; p=p->pLeft){



        int nNear = p->pParent->nNear;
        Fts3Phrase *pPhrase = (
            p->eType==FTSQUERY_NEAR ? p->pRight->pPhrase : p->pPhrase
        );
        res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
      }
    }

    sqlite3_free(aTmp);
................................................................................
    for(i=0; i<pPhrase->nToken; i++){
      fts3SegReaderCursorFree(pPhrase->aToken[i].pSegcsr);
      pPhrase->aToken[i].pSegcsr = 0;
    }
  }
}










#if !SQLITE_CORE
/*
** Initialize API pointer table, if required.
*/
SQLITE_API int sqlite3_extension_init(
  sqlite3 *db, 
  char **pzErrMsg,
................................................................................
**   FTS3 query "sqlite -mysql". Otherwise, ParseContext.isNot is set to
**   zero.
*/
typedef struct ParseContext ParseContext;
struct ParseContext {
  sqlite3_tokenizer *pTokenizer;      /* Tokenizer module */
  const char **azCol;                 /* Array of column names for fts3 table */

  int nCol;                           /* Number of entries in azCol[] */
  int iDefaultCol;                    /* Default column to query */
  int isNot;                          /* True if getNextNode() sees a unary - */
  sqlite3_context *pCtx;              /* Write error message here */
  int nNest;                          /* Number of nested brackets */
};

................................................................................
        pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
        memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);

        if( iEnd<n && z[iEnd]=='*' ){
          pRet->pPhrase->aToken[0].isPrefix = 1;
          iEnd++;
        }


        if( !sqlite3_fts3_enable_parentheses && iStart>0 && z[iStart-1]=='-' ){


          pParse->isNot = 1;






        }


      }
      nConsumed = iEnd;
    }

    pModule->xClose(pCursor);
  }
  
................................................................................
        memset(pToken, 0, sizeof(Fts3PhraseToken));

        memcpy(&zTemp[nTemp], zByte, nByte);
        nTemp += nByte;

        pToken->n = nByte;
        pToken->isPrefix = (iEnd<nInput && zInput[iEnd]=='*');

        nToken = ii+1;
      }
    }

    pModule->xClose(pCursor);
    pCursor = 0;
  }
................................................................................
    memset(p, 0, (char *)&(((Fts3Phrase *)&p[1])->aToken[0])-(char *)p);
    p->eType = FTSQUERY_PHRASE;
    p->pPhrase = (Fts3Phrase *)&p[1];
    p->pPhrase->iColumn = pParse->iDefaultCol;
    p->pPhrase->nToken = nToken;

    zBuf = (char *)&p->pPhrase->aToken[nToken];

    memcpy(zBuf, zTemp, nTemp);
    sqlite3_free(zTemp);




    for(jj=0; jj<p->pPhrase->nToken; jj++){
      p->pPhrase->aToken[jj].z = zBuf;
      zBuf += p->pPhrase->aToken[jj].n;
    }
    rc = SQLITE_OK;
  }
................................................................................
** column to match against for tokens for which a column name is not explicitly
** specified as part of the query string), or -1 if tokens may by default
** match any table column.
*/
SQLITE_PRIVATE int sqlite3Fts3ExprParse(
  sqlite3_tokenizer *pTokenizer,      /* Tokenizer module */
  char **azCol,                       /* Array of column names for fts3 table */

  int nCol,                           /* Number of entries in azCol[] */
  int iDefaultCol,                    /* Default column to query */
  const char *z, int n,               /* Text of MATCH query */
  Fts3Expr **ppExpr                   /* OUT: Parsed query structure */
){
  int nParsed;
  int rc;
  ParseContext sParse;
  sParse.pTokenizer = pTokenizer;
  sParse.azCol = (const char **)azCol;
  sParse.nCol = nCol;
  sParse.iDefaultCol = iDefaultCol;
  sParse.nNest = 0;

  if( z==0 ){
    *ppExpr = 0;
    return SQLITE_OK;
  }
  if( n<0 ){
    n = (int)strlen(z);
  }
................................................................................
    goto exprtest_out;
  }
  for(ii=0; ii<nCol; ii++){
    azCol[ii] = (char *)sqlite3_value_text(argv[ii+2]);
  }

  rc = sqlite3Fts3ExprParse(
      pTokenizer, azCol, nCol, nCol, zExpr, nExpr, &pExpr
  );
  if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM ){
    sqlite3_result_error(context, "Error parsing expression", -1);
  }else if( rc==SQLITE_NOMEM || !(zBuf = exprToString(pExpr, 0)) ){
    sqlite3_result_error_nomem(context);
  }else{
    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
................................................................................
/* 0  */  "DELETE FROM %Q.'%q_content' WHERE rowid = ?",
/* 1  */  "SELECT NOT EXISTS(SELECT docid FROM %Q.'%q_content' WHERE rowid!=?)",
/* 2  */  "DELETE FROM %Q.'%q_content'",
/* 3  */  "DELETE FROM %Q.'%q_segments'",
/* 4  */  "DELETE FROM %Q.'%q_segdir'",
/* 5  */  "DELETE FROM %Q.'%q_docsize'",
/* 6  */  "DELETE FROM %Q.'%q_stat'",
/* 7  */  "SELECT %s FROM %Q.'%q_content' AS x WHERE rowid=?",
/* 8  */  "SELECT (SELECT max(idx) FROM %Q.'%q_segdir' WHERE level = ?) + 1",
/* 9  */  "INSERT INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",

          /* Return segments in order from oldest to newest.*/ 
/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
................................................................................
  
  pStmt = p->aStmt[eStmt];
  if( !pStmt ){
    char *zSql;
    if( eStmt==SQL_CONTENT_INSERT ){
      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName, p->zWriteExprlist);
    }else if( eStmt==SQL_SELECT_CONTENT_BY_ROWID ){
      zSql = sqlite3_mprintf(azSql[eStmt], p->zReadExprlist, p->zDb, p->zName);
    }else{
      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName);
    }
    if( !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, NULL);
................................................................................
  if( rc==SQLITE_OK ){
    if( eStmt==SQL_SELECT_DOCSIZE ){
      sqlite3_bind_int64(pStmt, 1, iDocid);
    }
    rc = sqlite3_step(pStmt);
    if( rc!=SQLITE_ROW || sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB ){
      rc = sqlite3_reset(pStmt);
      if( rc==SQLITE_OK ) rc = SQLITE_CORRUPT_VTAB;
      pStmt = 0;
    }else{
      rc = SQLITE_OK;
    }
  }

  *ppStmt = pStmt;
................................................................................
** write-locks on the %_segments and %_segdir ** tables). 
**
** We try to avoid this because if FTS3 returns any error when committing
** a transaction, the whole transaction will be rolled back. And this is
** not what users expect when they get SQLITE_LOCKED_SHAREDCACHE. It can
** still happen if the user reads data directly from the %_segments or
** %_segdir tables instead of going through FTS3 though.


*/
SQLITE_PRIVATE int sqlite3Fts3ReadLock(Fts3Table *p){
  int rc;                         /* Return code */
  sqlite3_stmt *pStmt;            /* Statement used to obtain lock */


  rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pStmt, 0);
  if( rc==SQLITE_OK ){
    sqlite3_bind_null(pStmt, 1);
    sqlite3_step(pStmt);
    rc = sqlite3_reset(pStmt);
  }




  return rc;
}

/*
** Set *ppStmt to a statement handle that may be used to iterate through
** all rows in the %_segdir table, from oldest to newest. If successful,
** return SQLITE_OK. If an error occurs while preparing the statement, 
................................................................................
static int fts3InsertData(
  Fts3Table *p,                   /* Full-text table */
  sqlite3_value **apVal,          /* Array of values to insert */
  sqlite3_int64 *piDocid          /* OUT: Docid for row just inserted */
){
  int rc;                         /* Return code */
  sqlite3_stmt *pContentInsert;   /* INSERT INTO %_content VALUES(...) */













  /* Locate the statement handle used to insert data into the %_content
  ** table. The SQL for this statement is:
  **
  **   INSERT INTO %_content VALUES(?, ?, ?, ...)
  **
  ** The statement features N '?' variables, where N is the number of user
................................................................................



/*
** Remove all data from the FTS3 table. Clear the hash table containing
** pending terms.
*/
static int fts3DeleteAll(Fts3Table *p){
  int rc = SQLITE_OK;             /* Return code */

  /* Discard the contents of the pending-terms hash table. */
  sqlite3Fts3PendingTermsClear(p);

  /* Delete everything from the %_content, %_segments and %_segdir tables. */


  fts3SqlExec(&rc, p, SQL_DELETE_ALL_CONTENT, 0);
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGMENTS, 0);
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
  if( p->bHasDocsize ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_DOCSIZE, 0);
  }
  if( p->bHasStat ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_STAT, 0);
................................................................................
  /* Because of the FTS3_NODE_PADDING bytes of padding, the following is 
  ** safe (no risk of overread) even if the node data is corrupted. */
  pNext += sqlite3Fts3GetVarint32(pNext, &nPrefix);
  pNext += sqlite3Fts3GetVarint32(pNext, &nSuffix);
  if( nPrefix<0 || nSuffix<=0 
   || &pNext[nSuffix]>&pReader->aNode[pReader->nNode] 
  ){
    return SQLITE_CORRUPT_VTAB;
  }

  if( nPrefix+nSuffix>pReader->nTermAlloc ){
    int nNew = (nPrefix+nSuffix)*2;
    char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
    if( !zNew ){
      return SQLITE_NOMEM;
................................................................................
  /* Check that the doclist does not appear to extend past the end of the
  ** b-tree node. And that the final byte of the doclist is 0x00. If either 
  ** of these statements is untrue, then the data structure is corrupt.
  */
  if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
   || (pReader->nPopulate==0 && pReader->aDoclist[pReader->nDoclist-1])
  ){
    return SQLITE_CORRUPT_VTAB;
  }
  return SQLITE_OK;
}

/*
** Set the SegReader to point to the first docid in the doclist associated
** with the current term.
................................................................................
** If successful, *pisEmpty is set to true if the table is empty except for
** document pRowid, or false otherwise, and SQLITE_OK is returned. If an
** error occurs, an SQLite error code is returned.
*/
static int fts3IsEmpty(Fts3Table *p, sqlite3_value *pRowid, int *pisEmpty){
  sqlite3_stmt *pStmt;
  int rc;





  rc = fts3SqlStmt(p, SQL_IS_EMPTY, &pStmt, &pRowid);
  if( rc==SQLITE_OK ){
    if( SQLITE_ROW==sqlite3_step(pStmt) ){
      *pisEmpty = sqlite3_column_int(pStmt, 0);
    }
    rc = sqlite3_reset(pStmt);

  }
  return rc;
}

/*
** Set *pnMax to the largest segment level in the database for the index
** iIndex.
................................................................................
  int rc = SQLITE_OK;

  int isIgnoreEmpty =  (pCsr->pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
  int isRequirePos =   (pCsr->pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
  int isColFilter =    (pCsr->pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
  int isPrefix =       (pCsr->pFilter->flags & FTS3_SEGMENT_PREFIX);
  int isScan =         (pCsr->pFilter->flags & FTS3_SEGMENT_SCAN);


  Fts3SegReader **apSegment = pCsr->apSegment;
  int nSegment = pCsr->nSegment;
  Fts3SegFilter *pFilter = pCsr->pFilter;
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );
................................................................................
    ){
      nMerge++;
    }

    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
    if( nMerge==1 
     && !isIgnoreEmpty 

     && (p->bDescIdx==0 || fts3SegReaderIsPending(apSegment[0])==0)
    ){
      pCsr->nDoclist = apSegment[0]->nDoclist;
      if( fts3SegReaderIsPending(apSegment[0]) ){
        rc = fts3MsrBufferData(pCsr, apSegment[0]->aDoclist, pCsr->nDoclist);
        pCsr->aDoclist = pCsr->aBuffer;
      }else{
................................................................................
            pCsr->nBuffer = (nDoclist+nByte)*2;
            aNew = sqlite3_realloc(pCsr->aBuffer, pCsr->nBuffer);
            if( !aNew ){
              return SQLITE_NOMEM;
            }
            pCsr->aBuffer = aNew;
          }











          nDoclist += sqlite3Fts3PutVarint(&pCsr->aBuffer[nDoclist], iDelta);
          iPrev = iDocid;
          if( isRequirePos ){
            memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
            nDoclist += nList;
            pCsr->aBuffer[nDoclist++] = '\0';

          }
        }

        fts3SegReaderSort(apSegment, nMerge, j, xCmp);
      }
      if( nDoclist>0 ){
        pCsr->aDoclist = pCsr->aBuffer;
................................................................................

/*
** Insert the sizes (in tokens) for each column of the document
** with docid equal to p->iPrevDocid.  The sizes are encoded as
** a blob of varints.
*/
static void fts3InsertDocsize(
  int *pRC,         /* Result code */
  Fts3Table *p,     /* Table into which to insert */
  u32 *aSz          /* Sizes of each column */
){
  char *pBlob;             /* The BLOB encoding of the document size */
  int nBlob;               /* Number of bytes in the BLOB */
  sqlite3_stmt *pStmt;     /* Statement used to insert the encoding */
  int rc;                  /* Result code from subfunctions */

  if( *pRC ) return;
................................................................................
    }
  }
  sqlite3Fts3SegmentsClose(p);
  sqlite3Fts3PendingTermsClear(p);

  return (rc==SQLITE_OK && bReturnDone && bSeenDone) ? SQLITE_DONE : rc;
}

















































































/*
** Handle a 'special' INSERT of the form:
**
**   "INSERT INTO tbl(tbl) VALUES(<expr>)"
**
** Argument pVal contains the result of <expr>. Currently the only 
................................................................................
  const char *zVal = (const char *)sqlite3_value_text(pVal);
  int nVal = sqlite3_value_bytes(pVal);

  if( !zVal ){
    return SQLITE_NOMEM;
  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
    rc = fts3DoOptimize(p, 0);


#ifdef SQLITE_TEST
  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
    p->nNodeSize = atoi(&zVal[9]);
    rc = SQLITE_OK;
  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
    p->nMaxPendingData = atoi(&zVal[11]);
    rc = SQLITE_OK;
................................................................................
        int iPos;                 /* Position of token in zText */
  
        pTC->pTokenizer = pT;
        rc = pModule->xNext(pTC, &zToken, &nToken, &iDum1, &iDum2, &iPos);
        for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
          Fts3PhraseToken *pPT = pDef->pToken;
          if( (pDef->iCol>=p->nColumn || pDef->iCol==i)

           && (pPT->n==nToken || (pPT->isPrefix && pPT->n<nToken))
           && (0==memcmp(zToken, pPT->z, pPT->n))
          ){
            fts3PendingListAppend(&pDef->pList, iDocid, i, iPos, &rc);
          }
        }
      }
................................................................................
  int isEmpty = 0;
  int rc = fts3IsEmpty(p, pRowid, &isEmpty);
  if( rc==SQLITE_OK ){
    if( isEmpty ){
      /* Deleting this row means the whole table is empty. In this case
      ** delete the contents of all three tables and throw away any
      ** data in the pendingTerms hash table.  */
      rc = fts3DeleteAll(p);
      *pnDoc = *pnDoc - 1;
    }else{
      sqlite3_int64 iRemove = sqlite3_value_int64(pRowid);
      rc = fts3PendingTermsDocid(p, iRemove);
      fts3DeleteTerms(&rc, p, pRowid, aSzDel);

      fts3SqlExec(&rc, p, SQL_DELETE_CONTENT, &pRowid);
      if( sqlite3_changes(p->db) ) *pnDoc = *pnDoc - 1;



      if( p->bHasDocsize ){
        fts3SqlExec(&rc, p, SQL_DELETE_DOCSIZE, &pRowid);
      }
    }
  }

  return rc;
................................................................................
  int nArg,                       /* Size of argument array */
  sqlite3_value **apVal,          /* Array of arguments */
  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  int rc = SQLITE_OK;             /* Return Code */
  int isRemove = 0;               /* True for an UPDATE or DELETE */
  sqlite3_int64 iRemove = 0;      /* Rowid removed by UPDATE or DELETE */
  u32 *aSzIns = 0;                /* Sizes of inserted documents */
  u32 *aSzDel;                    /* Sizes of deleted documents */
  int nChng = 0;                  /* Net change in number of documents */
  int bInsertDone = 0;

  assert( p->pSegments==0 );

................................................................................
  **
  ** If the on-conflict mode is REPLACE, this means that the existing row
  ** should be deleted from the database before inserting the new row. Or,
  ** if the on-conflict mode is other than REPLACE, then this method must
  ** detect the conflict and return SQLITE_CONSTRAINT before beginning to
  ** modify the database file.
  */
  if( nArg>1 ){
    /* Find the value object that holds the new rowid value. */
    sqlite3_value *pNewRowid = apVal[3+p->nColumn];
    if( sqlite3_value_type(pNewRowid)==SQLITE_NULL ){
      pNewRowid = apVal[1];
    }

    if( sqlite3_value_type(pNewRowid)!=SQLITE_NULL && ( 
................................................................................
  }

  /* If this is a DELETE or UPDATE operation, remove the old record. */
  if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
    assert( sqlite3_value_type(apVal[0])==SQLITE_INTEGER );
    rc = fts3DeleteByRowid(p, apVal[0], &nChng, aSzDel);
    isRemove = 1;
    iRemove = sqlite3_value_int64(apVal[0]);
  }
  
  /* If this is an INSERT or UPDATE operation, insert the new record. */
  if( nArg>1 && rc==SQLITE_OK ){
    if( bInsertDone==0 ){
      rc = fts3InsertData(p, apVal, pRowid);
      if( rc==SQLITE_CONSTRAINT ) rc = SQLITE_CORRUPT_VTAB;

    }

    if( rc==SQLITE_OK && (!isRemove || *pRowid!=iRemove) ){
      rc = fts3PendingTermsDocid(p, *pRowid);
    }
    if( rc==SQLITE_OK ){

      rc = fts3InsertTerms(p, apVal, aSzIns);
    }
    if( p->bHasDocsize ){
      fts3InsertDocsize(&rc, p, aSzIns);
    }
    nChng++;
  }
................................................................................
  pPhrase->nToken = pExpr->pPhrase->nToken;

  pCsr = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol);
  if( pCsr ){
    int iFirst = 0;
    pPhrase->pList = pCsr;
    fts3GetDeltaPosition(&pCsr, &iFirst);

    pPhrase->pHead = pCsr;
    pPhrase->pTail = pCsr;
    pPhrase->iHead = iFirst;
    pPhrase->iTail = iFirst;
  }else{
    assert( pPhrase->pList==0 && pPhrase->pHead==0 && pPhrase->pTail==0 );
  }
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  pStmt = *ppStmt;
  assert( sqlite3_data_count(pStmt)==1 );

  a = sqlite3_column_blob(pStmt, 0);
  a += sqlite3Fts3GetVarint(a, &nDoc);
  if( nDoc==0 ) return SQLITE_CORRUPT_VTAB;
  *pnDoc = (u32)nDoc;

  if( paLen ) *paLen = a;
  return SQLITE_OK;
}

/*
................................................................................
          iMinPos = pT->iPos-pT->iOff;
          pTerm = pT;
        }
      }

      if( !pTerm ){
        /* All offsets for this column have been gathered. */
        break;
      }else{
        assert( iCurrent<=iMinPos );
        if( 0==(0xFE&*pTerm->pList) ){
          pTerm->pList = 0;
        }else{
          fts3GetDeltaPosition(&pTerm->pList, &pTerm->iPos);
        }
................................................................................
        }
        if( rc==SQLITE_OK ){
          char aBuffer[64];
          sqlite3_snprintf(sizeof(aBuffer), aBuffer, 
              "%d %d %d %d ", iCol, pTerm-sCtx.aTerm, iStart, iEnd-iStart
          );
          rc = fts3StringAppend(&res, aBuffer, -1);
        }else if( rc==SQLITE_DONE ){
          rc = SQLITE_CORRUPT_VTAB;
        }
      }
    }
    if( rc==SQLITE_DONE ){
      rc = SQLITE_OK;
    }

................................................................................
    if( argc>0 ){
      pCsr->aConstraint = sqlite3_malloc(sizeof(RtreeConstraint)*argc);
      pCsr->nConstraint = argc;
      if( !pCsr->aConstraint ){
        rc = SQLITE_NOMEM;
      }else{
        memset(pCsr->aConstraint, 0, sizeof(RtreeConstraint)*argc);
        assert( (idxStr==0 && argc==0) || (int)strlen(idxStr)==argc*2 );

        for(ii=0; ii<argc; ii++){
          RtreeConstraint *p = &pCsr->aConstraint[ii];
          p->op = idxStr[ii*2];
          p->iCoord = idxStr[ii*2+1]-'a';
          if( p->op==RTREE_MATCH ){
            /* A MATCH operator. The right-hand-side must be a blob that
            ** can be cast into an RtreeMatchArg object. One created using
................................................................................

  for(ii=0; rc==SQLITE_OK && ii<(pRtree->iDepth-iHeight); ii++){
    int iCell;
    sqlite3_int64 iBest = 0;

    float fMinGrowth = 0.0;
    float fMinArea = 0.0;

    float fMinOverlap = 0.0;



    int nCell = NCELL(pNode);
    RtreeCell cell;
    RtreeNode *pChild;

    RtreeCell *aCell = 0;

................................................................................
    ** is inserted into it. Resolve ties by choosing the entry with
    ** the smallest area.
    */
    for(iCell=0; iCell<nCell; iCell++){
      int bBest = 0;
      float growth;
      float area;
      float overlap = 0.0;
      nodeGetCell(pRtree, pNode, iCell, &cell);
      growth = cellGrowth(pRtree, &cell, pCell);
      area = cellArea(pRtree, &cell);

#if VARIANT_RSTARTREE_CHOOSESUBTREE
      if( ii==(pRtree->iDepth-1) ){
        overlap = cellOverlapEnlargement(pRtree,&cell,pCell,aCell,nCell,iCell);


      }
      if( (iCell==0) 
       || (overlap<fMinOverlap) 
       || (overlap==fMinOverlap && growth<fMinGrowth)
       || (overlap==fMinOverlap && growth==fMinGrowth && area<fMinArea)
      ){
        bBest = 1;

      }
#else
      if( iCell==0||growth<fMinGrowth||(growth==fMinGrowth && area<fMinArea) ){
        bBest = 1;
      }
#endif
      if( bBest ){
        fMinOverlap = overlap;
        fMinGrowth = growth;
        fMinArea = area;
        iBest = cell.iRowid;
      }
    }

    sqlite3_free(aCell);

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.7.9.  By combining all the individual C code files into this 
** single large file, the entire code can be compiled as a single translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other
................................................................................
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_INTTYPES_H
#include <inttypes.h>
#endif








/*
** The following macros are used to cast pointers to integers and
** integers to pointers.  The way you do this varies from one compiler
** to the next, so we have developed the following set of #if statements
** to generate appropriate macros for a wide range of compilers.
**
** The correct "ANSI" way to do this is to use the intptr_t type. 
................................................................................
**
** On Windows, if the SQLITE_WIN32_MALLOC_VALIDATE macro is defined and the
** assert() macro is enabled, each call into the Win32 native heap subsystem
** will cause HeapValidate to be called.  If heap validation should fail, an
** assertion will be triggered.
**
** (Historical note:  There used to be several other options, but we've
** pared it down to just these three.)
**
** If none of the above are defined, then set SQLITE_SYSTEM_MALLOC as
** the default.
*/
#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_WIN32_MALLOC)+defined(SQLITE_MEMDEBUG)>1
# error "At most one of the following compile-time configuration options\
 is allows: SQLITE_SYSTEM_MALLOC, SQLITE_WIN32_MALLOC, SQLITE_MEMDEBUG"
................................................................................
** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.9"
#define SQLITE_VERSION_NUMBER 3007009
#define SQLITE_SOURCE_ID      "2011-10-29 15:29:43 fb15f5458eb3e17ce9795c09bffe1224fea0eecd"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode.  If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
**
** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
** a write transaction to indicate that, unless it is rolled back for some
** reason, the entire database file will be overwritten by the current 
** transaction. This is used by VACUUM operations.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7
#define SQLITE_FCNTL_SYNC_OMITTED     8
#define SQLITE_FCNTL_WIN32_AV_RETRY   9
#define SQLITE_FCNTL_PERSIST_WAL     10
#define SQLITE_FCNTL_OVERWRITE       11

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
................................................................................
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.
** The minimum allocation size is capped at 2**12. Reasonable values
** for the minimum allocation size are 2**5 through 2**8.</dd>
**
** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
................................................................................
** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes as this saves SQLite from having to
** make a copy of the input string.
**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
................................................................................
** WHERE clause might influence the choice of query plan for a statement,
** then the statement will be automatically recompiled, as if there had been 
** a schema change, on the first  [sqlite3_step()] call following any change
** to the [sqlite3_bind_text | bindings] of that [parameter]. 
** ^The specific value of WHERE-clause [parameter] might influence the 
** choice of query plan if the parameter is the left-hand side of a [LIKE]
** or [GLOB] operator or if the parameter is compared to an indexed column
** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
** the 
** </li>
** </ol>
*/
SQLITE_API int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
................................................................................
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.
** If a non-negative fourth parameter is provided to sqlite3_bind_text()
** or sqlite3_bind_text16() then that parameter must be the byte offset
** where the NUL terminator would occur assuming the string were NUL
** terminated.  If any NUL characters occur at byte offsets less than 
** the value of the fourth parameter then the resulting string value will
** contain embedded NULs.  The result of expressions involving strings
** with embedded NULs is undefined.
**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called
** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
** ^If the fifth argument is
................................................................................
**
** ^The sqlite3_data_count(P) interface returns the number of columns in the
** current row of the result set of [prepared statement] P.
** ^If prepared statement P does not have results ready to return
** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
** interfaces) then sqlite3_data_count(P) returns 0.
** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
** will return non-zero if previous call to [sqlite3_step](P) returned
** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
** where it always returns zero since each step of that multi-step
** pragma returns 0 columns of data.
**
** See also: [sqlite3_column_count()]
*/
SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes
................................................................................
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.  If the 3rd parameter is non-negative, then it
** must be the byte offset into the string where the NUL terminator would
** appear if the string where NUL terminated.  If any NUL characters occur
** in the string at a byte offset that is less than the value of the 3rd
** parameter, then the resulting string will contain embedded NULs and the
** result of expressions operating on strings with embedded NULs is undefined.
** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not
................................................................................
**
** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
** <dd>This parameter returns the approximate number of of bytes of heap
** and lookaside memory used by all prepared statements associated with
** the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
** </dd>
**
** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
** <dd>This parameter returns the number of pager cache hits that have
** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT 
** is always 0.
** </dd>
**
** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
** <dd>This parameter returns the number of pager cache misses that have
** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS 
** is always 0.
** </dd>
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
#define SQLITE_DBSTATUS_CACHE_USED           1
#define SQLITE_DBSTATUS_SCHEMA_USED          2
#define SQLITE_DBSTATUS_STMT_USED            3
#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
#define SQLITE_DBSTATUS_CACHE_HIT            7
#define SQLITE_DBSTATUS_CACHE_MISS           8
#define SQLITE_DBSTATUS_MAX                  8   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS counters] that measure the number
................................................................................
**
** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
** <dd>^This is the number of rows inserted into transient indices that
** were created automatically in order to help joins run faster.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance by adding permanent indices that do not
** need to be reinitialized each time the statement is run.</dd>

** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2
#define SQLITE_STMTSTATUS_AUTOINDEX         3

/*
................................................................................
** SQLITE_MAX_U32 is a u64 constant that is the maximum u64 value
** that can be stored in a u32 without loss of data.  The value
** is 0x00000000ffffffff.  But because of quirks of some compilers, we
** have to specify the value in the less intuitive manner shown:
*/
#define SQLITE_MAX_U32  ((((u64)1)<<32)-1)

/*
** The datatype used to store estimates of the number of rows in a
** table or index.  This is an unsigned integer type.  For 99.9% of
** the world, a 32-bit integer is sufficient.  But a 64-bit integer
** can be used at compile-time if desired.
*/
#ifdef SQLITE_64BIT_STATS
 typedef u64 tRowcnt;    /* 64-bit only if requested at compile-time */
#else
 typedef u32 tRowcnt;    /* 32-bit is the default */
#endif

/*
** Macros to determine whether the machine is big or little endian,
** evaluated at runtime.
*/
#ifdef SQLITE_AMALGAMATION
SQLITE_PRIVATE const int sqlite3one = 1;
#else
................................................................................
** Allowed values for the flags parameter to sqlite3PagerOpen().
**
** NOTE: These values must match the corresponding BTREE_ values in btree.h.
*/
#define PAGER_OMIT_JOURNAL  0x0001    /* Do not use a rollback journal */
#define PAGER_NO_READLOCK   0x0002    /* Omit readlocks on readonly files */
#define PAGER_MEMORY        0x0004    /* In-memory database */


/*
** Valid values for the second argument to sqlite3PagerLockingMode().
*/
#define PAGER_LOCKINGMODE_QUERY      -1
#define PAGER_LOCKINGMODE_NORMAL      0
#define PAGER_LOCKINGMODE_EXCLUSIVE   1
................................................................................
SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager*);
SQLITE_PRIVATE const sqlite3_vfs *sqlite3PagerVfs(Pager*);
SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
SQLITE_PRIVATE int sqlite3PagerNosync(Pager*);
SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);
SQLITE_PRIVATE void sqlite3PagerCacheStat(Pager *, int, int, int *);
SQLITE_PRIVATE void sqlite3PagerClearCache(Pager *);

/* Functions used to truncate the database file. */
SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager*,Pgno);

#if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL)
SQLITE_PRIVATE void *sqlite3PagerCodec(DbPage *);
#endif
................................................................................

#ifdef SQLITE_MUTEX_OMIT
/*
** If this is a no-op implementation, implement everything as macros.
*/
#define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)
#define sqlite3_mutex_free(X)
#define sqlite3_mutex_enter(X)    
#define sqlite3_mutex_try(X)      SQLITE_OK
#define sqlite3_mutex_leave(X)    
#define sqlite3_mutex_held(X)     ((void)(X),1)
#define sqlite3_mutex_notheld(X)  ((void)(X),1)
#define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)
#define sqlite3MutexInit()        SQLITE_OK
#define sqlite3MutexEnd()
#define MUTEX_LOGIC(X)
#else
#define MUTEX_LOGIC(X)            X
#endif /* defined(SQLITE_MUTEX_OMIT) */

/************** End of mutex.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/


/*
................................................................................
struct Table {
  char *zName;         /* Name of the table or view */
  int iPKey;           /* If not negative, use aCol[iPKey] as the primary key */
  int nCol;            /* Number of columns in this table */
  Column *aCol;        /* Information about each column */
  Index *pIndex;       /* List of SQL indexes on this table. */
  int tnum;            /* Root BTree node for this table (see note above) */
  tRowcnt nRowEst;     /* Estimated rows in table - from sqlite_stat1 table */
  Select *pSelect;     /* NULL for tables.  Points to definition if a view. */
  u16 nRef;            /* Number of pointers to this Table */
  u8 tabFlags;         /* Mask of TF_* values */
  u8 keyConf;          /* What to do in case of uniqueness conflict on iPKey */
  FKey *pFKey;         /* Linked list of all foreign keys in this table */
  char *zColAff;       /* String defining the affinity of each column */
#ifndef SQLITE_OMIT_CHECK
................................................................................
** algorithm to employ whenever an attempt is made to insert a non-unique
** element.
*/
struct Index {
  char *zName;     /* Name of this index */
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  tRowcnt *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
  u8 bUnordered;   /* Use this index for == or IN queries only */
  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */
#ifdef SQLITE_ENABLE_STAT3
  int nSample;             /* Number of elements in aSample[] */
  tRowcnt avgEq;           /* Average nEq value for key values not in aSample */
  IndexSample *aSample;    /* Samples of the left-most key */
#endif
};

/*
** Each sample stored in the sqlite_stat3 table is represented in memory 
** using a structure of this type.  See documentation at the top of the
** analyze.c source file for additional information.
*/
struct IndexSample {
  union {
    char *z;        /* Value if eType is SQLITE_TEXT or SQLITE_BLOB */
    double r;       /* Value if eType is SQLITE_FLOAT */
    i64 i;          /* Value if eType is SQLITE_INTEGER */
  } u;
  u8 eType;         /* SQLITE_NULL, SQLITE_INTEGER ... etc. */
  int nByte;        /* Size in byte of text or blob. */
  tRowcnt nEq;      /* Est. number of rows where the key equals this sample */
  tRowcnt nLt;      /* Est. number of rows where key is less than this sample */
  tRowcnt nDLt;     /* Est. number of distinct keys less than this sample */
};

/*
** Each token coming out of the lexer is an instance of
** this structure.  Tokens are also used as part of an expression.
**
** Note if Token.z==0 then Token.dyn and Token.n are undefined and
................................................................................
** and the WhereInfo.wctrlFlags member.
*/
#define WHERE_ORDERBY_NORMAL   0x0000 /* No-op */
#define WHERE_ORDERBY_MIN      0x0001 /* ORDER BY processing for min() func */
#define WHERE_ORDERBY_MAX      0x0002 /* ORDER BY processing for max() func */
#define WHERE_ONEPASS_DESIRED  0x0004 /* Want to do one-pass UPDATE/DELETE */
#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
#define WHERE_OMIT_OPEN_CLOSE  0x0010 /* Table cursors are already open */

#define WHERE_FORCE_TABLE      0x0020 /* Do not use an index-only search */
#define WHERE_ONETABLE_ONLY    0x0040 /* Only code the 1st table in pTabList */
#define WHERE_AND_ONLY         0x0080 /* Don't use indices for OR terms */

/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second
** half does the tail of the WHERE loop.  An instance of
** this structure is returned by the first half and passed
** into the second half to give some continuity.
................................................................................
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
SQLITE_PRIVATE   int sqlite3ViewGetColumnNames(Parse*,Table*);
#else
# define sqlite3ViewGetColumnNames(A,B) 0
#endif

SQLITE_PRIVATE void sqlite3DropTable(Parse*, SrcList*, int, int);
SQLITE_PRIVATE void sqlite3CodeDropTable(Parse*, Table*, int, int);
SQLITE_PRIVATE void sqlite3DeleteTable(sqlite3*, Table*);
#ifndef SQLITE_OMIT_AUTOINCREMENT
SQLITE_PRIVATE   void sqlite3AutoincrementBegin(Parse *pParse);
SQLITE_PRIVATE   void sqlite3AutoincrementEnd(Parse *pParse);
#else
# define sqlite3AutoincrementBegin(X)
# define sqlite3AutoincrementEnd(X)
................................................................................
SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8, 
                        void(*)(void*));
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *, const void*, int, u8);
#ifdef SQLITE_ENABLE_STAT3
SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *, u8, char *, int, int *);
#endif
SQLITE_PRIVATE int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);
SQLITE_PRIVATE void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
#ifndef SQLITE_AMALGAMATION
SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[];
SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[];
................................................................................
#  define sqlite3VtabRollback(X)
#  define sqlite3VtabCommit(X)
#  define sqlite3VtabInSync(db) 0
#  define sqlite3VtabLock(X) 
#  define sqlite3VtabUnlock(X)
#  define sqlite3VtabUnlockList(X)
#  define sqlite3VtabSavepoint(X, Y, Z) SQLITE_OK
#  define sqlite3GetVTable(X,Y)  ((VTable*)0)
#else
SQLITE_PRIVATE    void sqlite3VtabClear(sqlite3 *db, Table*);
SQLITE_PRIVATE    int sqlite3VtabSync(sqlite3 *db, char **);
SQLITE_PRIVATE    int sqlite3VtabRollback(sqlite3 *db);
SQLITE_PRIVATE    int sqlite3VtabCommit(sqlite3 *db);
SQLITE_PRIVATE    void sqlite3VtabLock(VTable *);
SQLITE_PRIVATE    void sqlite3VtabUnlock(VTable *);
SQLITE_PRIVATE    void sqlite3VtabUnlockList(sqlite3*);
SQLITE_PRIVATE    int sqlite3VtabSavepoint(sqlite3 *, int, int);
SQLITE_PRIVATE    VTable *sqlite3GetVTable(sqlite3*, Table*);
#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
#endif
SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);
SQLITE_PRIVATE void sqlite3VtabArgExtend(Parse*, Token*);
................................................................................
SQLITE_PRIVATE void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);

SQLITE_PRIVATE const char *sqlite3JournalModename(int);
SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
SQLITE_PRIVATE int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);

/* Declarations for functions in fkey.c. All of these are replaced by
** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
** key functionality is available. If OMIT_TRIGGER is defined but
................................................................................
*/
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config = {
   SQLITE_DEFAULT_MEMSTATUS,  /* bMemstat */
   1,                         /* bCoreMutex */
   SQLITE_THREADSAFE==1,      /* bFullMutex */
   SQLITE_USE_URI,            /* bOpenUri */
   0x7ffffffe,                /* mxStrlen */
   128,                       /* szLookaside */
   500,                       /* nLookaside */
   {0,0,0,0,0,0,0,0},         /* m */
   {0,0,0,0,0,0,0,0,0},       /* mutex */
   {0,0,0,0,0,0,0,0,0,0,0},   /* pcache */
   (void*)0,                  /* pHeap */
   0,                         /* nHeap */
   0, 0,                      /* mnHeap, mxHeap */
................................................................................
#endif
#ifdef SQLITE_ENABLE_OVERSIZE_CELL_CHECK
  "ENABLE_OVERSIZE_CELL_CHECK",
#endif
#ifdef SQLITE_ENABLE_RTREE
  "ENABLE_RTREE",
#endif
#ifdef SQLITE_ENABLE_STAT3
  "ENABLE_STAT3",
#endif
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
  "ENABLE_UNLOCK_NOTIFY",
#endif
#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
  "ENABLE_UPDATE_DELETE_LIMIT",
#endif
................................................................................
#endif
#ifdef SQLITE_OMIT_WSD
  "OMIT_WSD",
#endif
#ifdef SQLITE_OMIT_XFER_OPT
  "OMIT_XFER_OPT",
#endif



#ifdef SQLITE_PERFORMANCE_TRACE
  "PERFORMANCE_TRACE",
#endif
#ifdef SQLITE_PROXY_DEBUG
  "PROXY_DEBUG",
#endif
#ifdef SQLITE_SECURE_DELETE
................................................................................
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);
SQLITE_PRIVATE int sqlite3VdbeTransferError(Vdbe *p);

#ifdef SQLITE_OMIT_MERGE_SORT
# define sqlite3VdbeSorterInit(Y,Z)      SQLITE_OK
# define sqlite3VdbeSorterWrite(X,Y,Z)   SQLITE_OK
# define sqlite3VdbeSorterClose(Y,Z)
# define sqlite3VdbeSorterRowkey(Y,Z)    SQLITE_OK
# define sqlite3VdbeSorterRewind(X,Y,Z)  SQLITE_OK
................................................................................
      db->pnBytesFreed = 0;

      *pHighwater = 0;
      *pCurrent = nByte;

      break;
    }

    /*
    ** Set *pCurrent to the total cache hits or misses encountered by all
    ** pagers the database handle is connected to. *pHighwater is always set 
    ** to zero.
    */
    case SQLITE_DBSTATUS_CACHE_HIT:
    case SQLITE_DBSTATUS_CACHE_MISS: {
      int i;
      int nRet = 0;
      assert( SQLITE_DBSTATUS_CACHE_MISS==SQLITE_DBSTATUS_CACHE_HIT+1 );

      for(i=0; i<db->nDb; i++){
        if( db->aDb[i].pBt ){
          Pager *pPager = sqlite3BtreePager(db->aDb[i].pBt);
          sqlite3PagerCacheStat(pPager, op, resetFlag, &nRet);
        }
      }
      *pHighwater = 0;
      *pCurrent = nRet;
      break;
    }

    default: {
      rc = SQLITE_ERROR;
    }
  }
  sqlite3_mutex_leave(db->mutex);
  return rc;
................................................................................
  if( p->validTZ ){
    computeJD(p);
  }
  return 0;
}

/*
** Set the time to the current time reported by the VFS.
**
** Return the number of errors.
*/
static int setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
  sqlite3 *db = sqlite3_context_db_handle(context);
  if( sqlite3OsCurrentTimeInt64(db->pVfs, &p->iJD)==SQLITE_OK ){
    p->validJD = 1;
    return 0;
  }else{
    return 1;
  }
}

/*
** Attempt to parse the given string into a Julian Day Number.  Return
** the number of errors.
**
** The following are acceptable forms for the input string:
................................................................................
){
  double r;
  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    return setDateTimeToCurrent(context, p);

  }else if( sqlite3AtoF(zDate, &r, sqlite3Strlen30(zDate), SQLITE_UTF8) ){
    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
    p->validJD = 1;
    return 0;
  }
  return 1;
}
................................................................................
  DateTime *p
){
  int i;
  const unsigned char *z;
  int eType;
  memset(p, 0, sizeof(*p));
  if( argc==0 ){
    return setDateTimeToCurrent(context, p);
  }
  if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
                   || eType==SQLITE_INTEGER ){
    p->iJD = (sqlite3_int64)(sqlite3_value_double(argv[0])*86400000.0 + 0.5);
    p->validJD = 1;
  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
................................................................................
  int argc,
  sqlite3_value **argv
){
  time_t t;
  char *zFormat = (char *)sqlite3_user_data(context);
  sqlite3 *db;
  sqlite3_int64 iT;
  struct tm *pTm;
  struct tm sNow;
  char zBuf[20];

  UNUSED_PARAMETER(argc);
  UNUSED_PARAMETER(argv);

  db = sqlite3_context_db_handle(context);
  if( sqlite3OsCurrentTimeInt64(db->pVfs, &iT) ) return;
  t = iT/1000 - 10000*(sqlite3_int64)21086676;
#ifdef HAVE_GMTIME_R


  pTm = gmtime_r(&t, &sNow);


#else


  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
  pTm = gmtime(&t);

  if( pTm ) memcpy(&sNow, pTm, sizeof(sNow));
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));

#endif

  if( pTm ){
    strftime(zBuf, 20, zFormat, &sNow);
    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
  }
}
#endif

/*
** This function registered all of the above C functions as SQL
** functions.  This should be the only routine in this file with
** external linkage.
................................................................................

/*
** Register a VFS with the system.  It is harmless to register the same
** VFS multiple times.  The new VFS becomes the default if makeDflt is
** true.
*/
SQLITE_API int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
  MUTEX_LOGIC(sqlite3_mutex *mutex;)
#ifndef SQLITE_OMIT_AUTOINIT
  int rc = sqlite3_initialize();
  if( rc ) return rc;
#endif
  MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
  sqlite3_mutex_enter(mutex);
  vfsUnlink(pVfs);
  if( makeDflt || vfsList==0 ){
    pVfs->pNext = vfsList;
    vfsList = pVfs;
  }else{
    pVfs->pNext = vfsList->pNext;
................................................................................
** the public domain.  The original comments are included here for
** completeness.  They are very out-of-date but might be useful as
** an historical reference.  Most of the "enhancements" have been backed
** out so that the functionality is now the same as standard printf().
**
**************************************************************************
**
** This file contains code for a set of "printf"-like routines.  These
** routines format strings much like the printf() from the standard C
** library, though the implementation here has enhancements to support
** SQLlite.






































*/

/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
................................................................................
  if( N>0 ){
    sqlite3StrAccumAppend(pAccum, zSpaces, N);
  }
}

/*
** On machines with a small stack size, you can redefine the
** SQLITE_PRINT_BUF_SIZE to be something smaller, if desired.
*/
#ifndef SQLITE_PRINT_BUF_SIZE

# define SQLITE_PRINT_BUF_SIZE 70



#endif
#define etBUFSIZE SQLITE_PRINT_BUF_SIZE  /* Size of the output buffer */

/*

























** Render a string given by "fmt" into the StrAccum object.
*/
SQLITE_PRIVATE void sqlite3VXPrintf(
  StrAccum *pAccum,                  /* Accumulate results here */
  int useExtended,                   /* Allow extended %-conversions */
  const char *fmt,                   /* Format string */
  va_list ap                         /* arguments */
){
................................................................................
  etByte flag_blanksign;     /* True if " " flag is present */
  etByte flag_alternateform; /* True if "#" flag is present */
  etByte flag_altform2;      /* True if "!" flag is present */
  etByte flag_zeropad;       /* True if field width constant starts with zero */
  etByte flag_long;          /* True if "l" flag is present */
  etByte flag_longlong;      /* True if the "ll" flag is present */
  etByte done;               /* Loop termination flag */
  etByte xtype = 0;          /* Conversion paradigm */
  char prefix;               /* Prefix character.  "+" or "-" or " " or '\0'. */
  sqlite_uint64 longvalue;   /* Value for integer types */
  LONGDOUBLE_TYPE realvalue; /* Value for real types */
  const et_info *infop;      /* Pointer to the appropriate info structure */
  char *zOut;                /* Rendering buffer */
  int nOut;                  /* Size of the rendering buffer */

  char *zExtra;              /* Malloced memory used by some conversion */
#ifndef SQLITE_OMIT_FLOATING_POINT
  int  exp, e2;              /* exponent of real numbers */
  int nsd;                   /* Number of significant digits returned */
  double rounder;            /* Used for rounding floating point values */
  etByte flag_dp;            /* True if decimal point should be shown */
  etByte flag_rtz;           /* True if trailing zeros should be removed */


#endif
  char buf[etBUFSIZE];       /* Conversion buffer */


  bufpt = 0;
  for(; (c=(*fmt))!=0; ++fmt){
    if( c!='%' ){
      int amt;
      bufpt = (char *)fmt;
      amt = 1;
      while( (c=(*++fmt))!='%' && c!=0 ) amt++;
................................................................................
      c = *++fmt;
    }else{
      while( c>='0' && c<='9' ){
        width = width*10 + c - '0';
        c = *++fmt;
      }
    }



    /* Get the precision */
    if( c=='.' ){
      precision = 0;
      c = *++fmt;
      if( c=='*' ){
        precision = va_arg(ap,int);
        if( precision<0 ) precision = -precision;
................................................................................
          return;
        }
        break;
      }
    }
    zExtra = 0;







    /*
    ** At this point, variables are initialized as follows:
    **
    **   flag_alternateform          TRUE if a '#' is present.
    **   flag_altform2               TRUE if a '!' is present.
    **   flag_plussign               TRUE if a '+' is present.
    **   flag_leftjustify            TRUE if a '-' is present or if the
................................................................................
          }
          prefix = 0;
        }
        if( longvalue==0 ) flag_alternateform = 0;
        if( flag_zeropad && precision<width-(prefix!=0) ){
          precision = width-(prefix!=0);
        }
        if( precision<etBUFSIZE-10 ){
          nOut = etBUFSIZE;
          zOut = buf;
        }else{
          nOut = precision + 10;
          zOut = zExtra = sqlite3Malloc( nOut );
          if( zOut==0 ){
            pAccum->mallocFailed = 1;
            return;
          }
        }
        bufpt = &zOut[nOut-1];
        if( xtype==etORDINAL ){
          static const char zOrd[] = "thstndrd";
          int x = (int)(longvalue % 10);
          if( x>=4 || (longvalue/10)%10==1 ){
            x = 0;
          }
          *(--bufpt) = zOrd[x*2+1];
          *(--bufpt) = zOrd[x*2];

        }
        {
          register const char *cset;      /* Use registers for speed */
          register int base;
          cset = &aDigits[infop->charset];
          base = infop->base;
          do{                                           /* Convert to ascii */
            *(--bufpt) = cset[longvalue%base];
            longvalue = longvalue/base;
          }while( longvalue>0 );
        }
        length = (int)(&zOut[nOut-1]-bufpt);
        for(idx=precision-length; idx>0; idx--){
          *(--bufpt) = '0';                             /* Zero pad */
        }
        if( prefix ) *(--bufpt) = prefix;               /* Add sign */
        if( flag_alternateform && infop->prefix ){      /* Add "0" or "0x" */
          const char *pre;
          char x;
          pre = &aPrefix[infop->prefix];
          for(; (x=(*pre))!=0; pre++) *(--bufpt) = x;
        }
        length = (int)(&zOut[nOut-1]-bufpt);
        break;
      case etFLOAT:
      case etEXP:
      case etGENERIC:
        realvalue = va_arg(ap,double);
#ifdef SQLITE_OMIT_FLOATING_POINT
        length = 0;
#else
        if( precision<0 ) precision = 6;         /* Set default precision */

        if( realvalue<0.0 ){
          realvalue = -realvalue;
          prefix = '-';
        }else{
          if( flag_plussign )          prefix = '+';
          else if( flag_blanksign )    prefix = ' ';
          else                         prefix = 0;
................................................................................
          }
        }
        bufpt = buf;
        /*
        ** If the field type is etGENERIC, then convert to either etEXP
        ** or etFLOAT, as appropriate.
        */

        if( xtype!=etFLOAT ){
          realvalue += rounder;
          if( realvalue>=10.0 ){ realvalue *= 0.1; exp++; }
        }
        if( xtype==etGENERIC ){
          flag_rtz = !flag_alternateform;
          if( exp<-4 || exp>precision ){
................................................................................
          flag_rtz = 0;
        }
        if( xtype==etEXP ){
          e2 = 0;
        }else{
          e2 = exp;
        }
        if( e2+precision+width > etBUFSIZE - 15 ){
          bufpt = zExtra = sqlite3Malloc( e2+precision+width+15 );
          if( bufpt==0 ){
            pAccum->mallocFailed = 1;
            return;
          }
        }
        zOut = bufpt;
        nsd = 0;
        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
        /* The sign in front of the number */
        if( prefix ){
          *(bufpt++) = prefix;
        }
        /* Digits prior to the decimal point */
................................................................................
        /* Significant digits after the decimal point */
        while( (precision--)>0 ){
          *(bufpt++) = et_getdigit(&realvalue,&nsd);
        }
        /* Remove trailing zeros and the "." if no digits follow the "." */
        if( flag_rtz && flag_dp ){
          while( bufpt[-1]=='0' ) *(--bufpt) = 0;
          assert( bufpt>zOut );
          if( bufpt[-1]=='.' ){
            if( flag_altform2 ){
              *(bufpt++) = '0';
            }else{
              *(--bufpt) = 0;
            }
          }
        }
        /* Add the "eNNN" suffix */
        if( xtype==etEXP ){
          *(bufpt++) = aDigits[infop->charset];
          if( exp<0 ){
            *(bufpt++) = '-'; exp = -exp;
          }else{
            *(bufpt++) = '+';
          }
          if( exp>=100 ){
................................................................................
          *(bufpt++) = (char)(exp%10+'0');             /* 1's digit */
        }
        *bufpt = 0;

        /* The converted number is in buf[] and zero terminated. Output it.
        ** Note that the number is in the usual order, not reversed as with
        ** integer conversions. */
        length = (int)(bufpt-zOut);
        bufpt = zOut;

        /* Special case:  Add leading zeros if the flag_zeropad flag is
        ** set and we are not left justified */
        if( flag_zeropad && !flag_leftjustify && length < width){
          int i;
          int nPad = width - length;
          for(i=width; i>=nPad; i--){
................................................................................
    if( flag_leftjustify ){
      register int nspace;
      nspace = width-length;
      if( nspace>0 ){
        appendSpace(pAccum, nspace);
      }
    }

    sqlite3_free(zExtra);

  }/* End for loop over the format string */
} /* End of function */

/*
** Append N bytes of text from z to the StrAccum object.
*/
SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
  assert( z!=0 || N==0 );
  if( p->tooBig | p->mallocFailed ){
    testcase(p->tooBig);
    testcase(p->mallocFailed);
    return;
  }
  assert( p->zText!=0 || p->nChar==0 );
  if( N<0 ){
    N = sqlite3Strlen30(z);
  }
  if( N==0 || NEVER(z==0) ){
    return;
  }
  if( p->nChar+N >= p->nAlloc ){
................................................................................
      }
      if( p->useMalloc==1 ){
        zNew = sqlite3DbRealloc(p->db, zOld, p->nAlloc);
      }else{
        zNew = sqlite3_realloc(zOld, p->nAlloc);
      }
      if( zNew ){
        if( zOld==0 && p->nChar>0 ) memcpy(zNew, p->zText, p->nChar);
        p->zText = zNew;
      }else{
        p->mallocFailed = 1;
        sqlite3StrAccumReset(p);
        return;
      }
    }
  }
  assert( p->zText );
  memcpy(&p->zText[p->nChar], z, N);
  p->nChar += N;
}

/*
** Finish off a string by making sure it is zero-terminated.
** Return a pointer to the resulting string.  Return a NULL
................................................................................
** is set to the length of the returned string in bytes. The call should
** arrange to call sqlite3DbFree() on the returned pointer when it is
** no longer required.
** 
** If a malloc failure occurs, NULL is returned and the db.mallocFailed
** flag set.
*/
#ifdef SQLITE_ENABLE_STAT3
SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *db, u8 enc, char *z, int n, int *pnOut){
  Mem m;
  memset(&m, 0, sizeof(m));
  m.db = db;
  sqlite3VdbeMemSetStr(&m, z, n, SQLITE_UTF8, SQLITE_STATIC);
  if( sqlite3VdbeMemTranslate(&m, enc) ){
    assert( db->mallocFailed );
................................................................................
      esign = -1;
      z+=incr;
    }else if( *z=='+' ){
      z+=incr;
    }
    /* copy digits to exponent */
    while( z<zEnd && sqlite3Isdigit(*z) ){
      e = e<10000 ? (e*10 + (*z - '0')) : 10000;
      z+=incr;
      eValid = 1;
    }
  }

  /* skip trailing spaces */
  if( nDigits && eValid ){
................................................................................
        if( esign<0 ){
          result = s / scale;
          result /= 1.0e+308;
        }else{
          result = s * scale;
          result *= 1.0e+308;
        }
      }else if( e>=342 ){
        if( esign<0 ){
          result = 0.0*s;
        }else{
          result = 1e308*1e308*s;  /* Infinity */
        }
      }else{
        /* 1.0e+22 is the largest power of 10 than can be 
        ** represented exactly. */
        while( e%22 ) { scale *= 1.0e+1; e -= 1; }
        while( e>0 ) { scale *= 1.0e+22; e -= 22; }
        if( esign<0 ){
          result = s / scale;
................................................................................
#ifdef SQLITE_DEBUG
static int unixMutexHeld(void) {
  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
#endif


#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
/*
** Helper function for printing out trace information from debugging
** binaries. This returns the string represetation of the supplied
** integer lock-type.
*/
static const char *azFileLock(int eFileLock){
  switch( eFileLock ){
................................................................................
  ** The reason a single byte cannot be used instead of the 'shared byte
  ** range' is that some versions of windows do not support read-locks. By
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int tErrno = 0;

  assert( pFile );
  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
      azFileLock(eFileLock), azFileLock(pFile->eFileLock),
      azFileLock(pFile->pInode->eFileLock), pFile->pInode->nShared , getpid()));

  /* If there is already a lock of this type or more restrictive on the
  ** unixFile, do nothing. Don't use the end_lock: exit path, as
  ** unixEnterMutex() hasn't been called yet.
  */
  if( pFile->eFileLock>=eFileLock ){
    OSTRACE(("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
................................................................................
** remove the write lock on a region when a read lock is set.
*/
static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int rc = SQLITE_OK;


  assert( pFile );
  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
      pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
      getpid()));

  assert( eFileLock<=SHARED_LOCK );
  if( pFile->eFileLock<=eFileLock ){
    return SQLITE_OK;
  }
  unixEnterMutex();

  pInode = pFile->pInode;
  assert( pInode->nShared!=0 );
  if( pFile->eFileLock>SHARED_LOCK ){
    assert( pInode->eFileLock==pFile->eFileLock );




#ifndef NDEBUG
    /* When reducing a lock such that other processes can start
    ** reading the database file again, make sure that the
    ** transaction counter was updated if any part of the database
    ** file changed.  If the transaction counter is not updated,
    ** other connections to the same file might not realize that
    ** the file has changed and hence might not know to flush their
    ** cache.  The use of a stale cache can lead to database corruption.
    */





    pFile->inNormalWrite = 0;
#endif

    /* downgrading to a shared lock on NFS involves clearing the write lock
    ** before establishing the readlock - to avoid a race condition we downgrade
    ** the lock in 2 blocks, so that part of the range will be covered by a 
    ** write lock until the rest is covered by a read lock:
................................................................................
    ** the lock.
    */
    pInode->nShared--;
    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;



      if( unixFileLock(pFile, &lock)==0 ){
        pInode->eFileLock = NO_LOCK;
      }else{
        rc = SQLITE_IOERR_UNLOCK;
	pFile->lastErrno = errno;
        pInode->eFileLock = NO_LOCK;
        pFile->eFileLock = NO_LOCK;
................................................................................
    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
    if( pShmNode->mutex==0 ){
      rc = SQLITE_NOMEM;
      goto shm_open_err;
    }

    if( pInode->bProcessLock==0 ){



      const char *zRO;
      int openFlags = O_RDWR | O_CREAT;
      zRO = sqlite3_uri_parameter(pDbFd->zPath, "readonly_shm");
      if( zRO && sqlite3GetBoolean(zRO) ){


        openFlags = O_RDONLY;
        pShmNode->isReadonly = 1;
      }
      pShmNode->h = robust_open(zShmFilename, openFlags, (sStat.st_mode&0777));
      if( pShmNode->h<0 ){
        if( pShmNode->h<0 ){
          rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
          goto shm_open_err;
        }
      }
  
      /* Check to see if another process is holding the dead-man switch.
................................................................................
  */
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
  assert( zFilename==0 || zFilename[0]=='/' 
    || pVfs->pAppData==(void*)&autolockIoFinder );
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  /* No locking occurs in temporary files */
  assert( zFilename!=0 || noLock );

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->zPath = zFilename;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
    pNew->ctrlFlags = UNIXFILE_EXCL;
  }else{
................................................................................

  else if( pLockingStyle == &dotlockIoMethods ){
    /* Dotfile locking uses the file path so it needs to be included in
    ** the dotlockLockingContext 
    */
    char *zLockFile;
    int nFilename;
    assert( zFilename!=0 );
    nFilename = (int)strlen(zFilename) + 6;
    zLockFile = (char *)sqlite3_malloc(nFilename);
    if( zLockFile==0 ){
      rc = SQLITE_NOMEM;
    }else{
      sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
    }
................................................................................
    ** the following naming conventions:
    **
    **   "<path to db>-journal"
    **   "<path to db>-wal"
    **   "<path to db>-journalNN"
    **   "<path to db>-walNN"
    **
    ** where NN is a decimal number. The NN naming schemes are 
    ** used by the test_multiplex.c module.
    */
    nDb = sqlite3Strlen30(zPath) - 1; 
#ifdef SQLITE_ENABLE_8_3_NAMES
    while( nDb>0 && !sqlite3Isalnum(zPath[nDb]) ) nDb--;
    if( nDb==0 || zPath[nDb]!='-' ) return SQLITE_OK;
#else
    while( zPath[nDb]!='-' ){

      assert( nDb>0 );
      assert( zPath[nDb]!='\n' );
      nDb--;
    }
#endif
    memcpy(zDb, zPath, nDb);
    zDb[nDb] = '\0';

    if( 0==osStat(zDb, &sStat) ){
      *pMode = sStat.st_mode & 0777;
    }else{
      rc = SQLITE_IOERR_FSTAT;
................................................................................
/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**
** On success, return SQLITE_OK.  Return SQLITE_ERROR if the time and date 
** cannot be found.
*/
static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){
  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
  int rc = SQLITE_OK;
#if defined(NO_GETTOD)
  time_t t;
  time(&t);
  *piNow = ((sqlite3_int64)t)*1000 + unixEpoch;
#elif OS_VXWORKS
  struct timespec sNow;
  clock_gettime(CLOCK_REALTIME, &sNow);
  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_nsec/1000000;
#else
  struct timeval sNow;
  if( gettimeofday(&sNow, 0)==0 ){
    *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_usec/1000;
  }else{
    rc = SQLITE_ERROR;
  }
#endif

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
  }
#endif
  UNUSED_PARAMETER(NotUsed);
  return rc;
}

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
  sqlite3_int64 i = 0;
  int rc;
  UNUSED_PARAMETER(NotUsed);
  rc = unixCurrentTimeInt64(0, &i);
  *prNow = i/86400000.0;
  return rc;
}

/*
** We added the xGetLastError() method with the intention of providing
** better low-level error messages when operating-system problems come up
** during SQLite operation.  But so far, none of that has been implemented
** in the core.  So this routine is never called.  For now, it is merely
................................................................................
           h, zName, dwDesiredAccess, 
           h==INVALID_HANDLE_VALUE ? "failed" : "ok"));

  if( h==INVALID_HANDLE_VALUE ){
    pFile->lastErrno = GetLastError();
    winLogError(SQLITE_CANTOPEN, "winOpen", zUtf8Name);
    free(zConverted);
    if( isReadWrite && !isExclusive ){
      return winOpen(pVfs, zName, id, 
             ((flags|SQLITE_OPEN_READONLY)&~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)), pOutFlags);
    }else{
      return SQLITE_CANTOPEN_BKPT;
    }
  }

................................................................................
  free(zConverted);
  return (void*)h;
}
static void winDlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
  UNUSED_PARAMETER(pVfs);
  getLastErrorMsg(nBuf, zBufOut);
}
static void (*winDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol))(void){
  UNUSED_PARAMETER(pVfs);
#if SQLITE_OS_WINCE
  /* The GetProcAddressA() routine is only available on wince. */
  return (void(*)(void))GetProcAddressA((HANDLE)pHandle, zSymbol);
#else
  /* All other windows platforms expect GetProcAddress() to take
  ** an Ansi string regardless of the _UNICODE setting */
  return (void(*)(void))GetProcAddress((HANDLE)pHandle, zSymbol);
#endif
}
static void winDlClose(sqlite3_vfs *pVfs, void *pHandle){
  UNUSED_PARAMETER(pVfs);
  FreeLibrary((HANDLE)pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define winDlOpen  0
  #define winDlError 0
  #define winDlSym   0
................................................................................
/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**
** On success, return SQLITE_OK.  Return SQLITE_ERROR if the time and date 
** cannot be found.
*/
static int winCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
  /* FILETIME structure is a 64-bit value representing the number of 
     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5). 
  */
  FILETIME ft;
  static const sqlite3_int64 winFiletimeEpoch = 23058135*(sqlite3_int64)8640000;
................................................................................
      (sqlite3_int64)2000000000 + (sqlite3_int64)2000000000 + (sqlite3_int64)294967296;

#if SQLITE_OS_WINCE
  SYSTEMTIME time;
  GetSystemTime(&time);
  /* if SystemTimeToFileTime() fails, it returns zero. */
  if (!SystemTimeToFileTime(&time,&ft)){
    return SQLITE_ERROR;
  }
#else
  GetSystemTimeAsFileTime( &ft );
#endif

  *piNow = winFiletimeEpoch +
            ((((sqlite3_int64)ft.dwHighDateTime)*max32BitValue) + 
................................................................................

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
  }
#endif
  UNUSED_PARAMETER(pVfs);
  return SQLITE_OK;
}

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int winCurrentTime(sqlite3_vfs *pVfs, double *prNow){
  int rc;
  sqlite3_int64 i;
  rc = winCurrentTimeInt64(pVfs, &i);
  if( !rc ){
    *prNow = i/86400000.0;
  }
  return rc;
................................................................................


typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;
typedef struct PGroup PGroup;




/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
** of one or more PCaches that are able to recycle each others unpinned
** pages when they are under memory pressure.  A PGroup is an instance of
** the following object.
**
** This page cache implementation works in one of two modes:
................................................................................
struct PGroup {
  sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
  int nMaxPage;                  /* Sum of nMax for purgeable caches */
  int nMinPage;                  /* Sum of nMin for purgeable caches */
  int mxPinned;                  /* nMaxpage + 10 - nMinPage */
  int nCurrentPage;              /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;   /* LRU list of unpinned pages */




};























































/* Each page cache is an instance of the following object.  Every
** open database file (including each in-memory database and each
** temporary or transient database) has a single page cache which
** is an instance of this object.
**
** Pointers to structures of this type are cast and returned as 
** opaque sqlite3_pcache* handles.
................................................................................
** a pointer to a block of szPage bytes of data and the return value is
** a pointer to the associated PgHdr1 structure.
**
**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X );
*/
#define PGHDR1_TO_PAGE(p)    (void*)(((char*)p) - p->pCache->szPage)
#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage)












/*
** Macros to enter and leave the PCache LRU mutex.
*/
#define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
#define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)

................................................................................
    iSize = sqlite3MallocSize(p);
    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
    return iSize;
  }
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */

































/*
** Allocate a new page object initially associated with cache pCache.
*/
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  int nByte = sizeof(PgHdr1) + pCache->szPage;

  PgHdr1 *p = 0;
  void *pPg;






























































































  /* The group mutex must be released before pcache1Alloc() is called. This
  ** is because it may call sqlite3_release_memory(), which assumes that 
  ** this mutex is not held. */
  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  pcache1LeaveMutex(pCache->pGroup);
  pPg = pcache1Alloc(nByte);
  pcache1EnterMutex(pCache->pGroup);

  if( pPg ){
    p = PAGE_TO_PGHDR1(pCache, pPg);
    if( pCache->bPurgeable ){
      pCache->pGroup->nCurrentPage++;
    }


  }

  return p;
}

/*
** Free a page object allocated by pcache1AllocPage().
**
** The pointer is allowed to be NULL, which is prudent.  But it turns out
** that the current implementation happens to never call this routine
** with a NULL pointer, so we mark the NULL test with ALWAYS().
*/
static void pcache1FreePage(PgHdr1 *p){
  if( ALWAYS(p) ){
    PCache1 *pCache = p->pCache;








































    assert( sqlite3_mutex_held(p->pCache->pGroup->mutex) );
    pcache1Free(PGHDR1_TO_PAGE(p));

    if( pCache->bPurgeable ){
      pCache->pGroup->nCurrentPage--;
    }
  }
}

/*
................................................................................
**
** nReq is the number of bytes of memory required. Once this much has
** been released, the function returns. The return value is the total number 
** of bytes of memory released.
*/
SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int nReq){
  int nFree = 0;



  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
  assert( sqlite3_mutex_notheld(pcache1.mutex) );
  if( pcache1.pStart==0 ){
    PgHdr1 *p;
    pcache1EnterMutex(&pcache1.grp);
    while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){
      nFree += pcache1MemSize(PGHDR1_TO_PAGE(p));
................................................................................
  u8 noSync;                  /* Do not sync the journal if true */
  u8 fullSync;                /* Do extra syncs of the journal for robustness */
  u8 ckptSyncFlags;           /* SYNC_NORMAL or SYNC_FULL for checkpoint */
  u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
  u8 tempFile;                /* zFilename is a temporary file */
  u8 readOnly;                /* True for a read-only database */
  u8 memDb;                   /* True to inhibit all file I/O */


  /**************************************************************************
  ** The following block contains those class members that change during
  ** routine opertion.  Class members not in this block are either fixed
  ** when the pager is first created or else only change when there is a
  ** significant mode change (such as changing the page_size, locking_mode,
  ** or the journal_mode).  From another view, these class members describe
................................................................................
  int pageSize;               /* Number of bytes in a page */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  i64 journalSizeLimit;       /* Size limit for persistent journal files */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  int (*xBusyHandler)(void*); /* Function to call when busy */
  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
  int nHit, nMiss;            /* Total cache hits and misses */
#ifdef SQLITE_TEST

  int nRead, nWrite;          /* Database pages read/written */
#endif
  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
#ifdef SQLITE_HAS_CODEC
  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
  void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
  void (*xCodecFree)(void*);             /* Destructor for the codec */
................................................................................
      if( needPagerReset ){
        pager_reset(pPager);
        needPagerReset = 0;
      }
      rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){

          pPager->journalOff = szJ;
          break;
        }else if( rc==SQLITE_IOERR_SHORT_READ ){
          /* If the journal has been truncated, simply stop reading and
          ** processing the journal. This might happen if the journal was
          ** not completely written and synced prior to a crash.  In that
          ** case, the database should have never been written in the
................................................................................
){
  int rc;                         /* Return code */
#if defined(SQLITE_DEBUG) || defined(SQLITE_CHECK_PAGES)
  PgHdr *p;                       /* For looping over pages */
#endif

  assert( pPager->pWal );
  assert( pList );
#ifdef SQLITE_DEBUG
  /* Verify that the page list is in accending order */
  for(p=pList; p && p->pDirty; p=p->pDirty){
    assert( p->pgno < p->pDirty->pgno );
  }
#endif

................................................................................
  ** pages belonging to the same sector.
  **
  ** The doNotSpill flag inhibits all cache spilling regardless of whether
  ** or not a sync is required.  This is set during a rollback.
  **
  ** Spilling is also prohibited when in an error state since that could
  ** lead to database corruption.   In the current implementaton it 
  ** is impossible for sqlite3PcacheFetch() to be called with createFlag==1
  ** while in the error state, hence it is impossible for this routine to
  ** be called in the error state.  Nevertheless, we include a NEVER()
  ** test for the error state as a safeguard against future changes.
  */

  if( NEVER(pPager->errCode) ) return SQLITE_OK;
  if( pPager->doNotSpill ) return SQLITE_OK;
  if( pPager->doNotSyncSpill && (pPg->flags & PGHDR_NEED_SYNC)!=0 ){
    return SQLITE_OK;
  }

  pPg->pDirty = 0;
................................................................................
  assert( (*ppPage)->pgno==pgno );
  assert( (*ppPage)->pPager==pPager || (*ppPage)->pPager==0 );

  if( (*ppPage)->pPager && !noContent ){
    /* In this case the pcache already contains an initialized copy of
    ** the page. Return without further ado.  */
    assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
    pPager->nHit++;
    return SQLITE_OK;

  }else{
    /* The pager cache has created a new page. Its content needs to 
    ** be initialized.  */


    pPg = *ppPage;
    pPg->pPager = pPager;

    /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
    ** number greater than this, or the unused locking-page, is requested. */
    if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
      rc = SQLITE_CORRUPT_BKPT;
................................................................................
        testcase( rc==SQLITE_NOMEM );
        sqlite3EndBenignMalloc();
      }
      memset(pPg->pData, 0, pPager->pageSize);
      IOTRACE(("ZERO %p %d\n", pPager, pgno));
    }else{
      assert( pPg->pPager==pPager );
      pPager->nMiss++;
      rc = readDbPage(pPg);
      if( rc!=SQLITE_OK ){
        goto pager_acquire_err;
      }
    }
    pager_set_pagehash(pPg);
  }
................................................................................
  a[7] = pPager->nMiss;
  a[8] = 0;  /* Used to be pPager->nOvfl */
  a[9] = pPager->nRead;
  a[10] = pPager->nWrite;
  return a;
}
#endif

/*
** Parameter eStat must be either SQLITE_DBSTATUS_CACHE_HIT or
** SQLITE_DBSTATUS_CACHE_MISS. Before returning, *pnVal is incremented by the
** current cache hit or miss count, according to the value of eStat. If the 
** reset parameter is non-zero, the cache hit or miss count is zeroed before 
** returning.
*/
SQLITE_PRIVATE void sqlite3PagerCacheStat(Pager *pPager, int eStat, int reset, int *pnVal){
  int *piStat;

  assert( eStat==SQLITE_DBSTATUS_CACHE_HIT
       || eStat==SQLITE_DBSTATUS_CACHE_MISS
  );
  if( eStat==SQLITE_DBSTATUS_CACHE_HIT ){
    piStat = &pPager->nHit;
  }else{
    piStat = &pPager->nMiss;
  }

  *pnVal += *piStat;
  if( reset ){
    *piStat = 0;
  }
}

/*
** Return true if this is an in-memory pager.
*/
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager *pPager){
  return MEMDB;
}
................................................................................
      rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
                           pPager->pageSize, (u8*)pPager->pTmpSpace);
      pPager->pWal = 0;
    }
  }
  return rc;
}

/*
** Unless this is an in-memory or temporary database, clear the pager cache.
*/
SQLITE_PRIVATE void sqlite3PagerClearCache(Pager *pPager){
  if( !MEMDB && pPager->tempFile==0 ) pager_reset(pPager);
}

#ifdef SQLITE_HAS_CODEC
/*
** This function is called by the wal module when writing page content
** into the log file.
**
** This function returns a pointer to a buffer containing the encrypted
................................................................................
  /* If iRead is non-zero, then it is the log frame number that contains the
  ** required page. Read and return data from the log file.
  */
  if( iRead ){
    int sz;
    i64 iOffset;
    sz = pWal->hdr.szPage;
    sz = (sz&0xfe00) + ((sz&0x0001)<<16);
    testcase( sz<=32768 );
    testcase( sz>=65536 );
    iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
    *pInWal = 1;
    /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
    return sqlite3OsRead(pWal->pWalFd, pOut, nOut, iOffset);
  }
................................................................................
  ** If this Btree is a candidate for shared cache, try to find an
  ** existing BtShared object that we can share with
  */
  if( isMemdb==0 && isTempDb==0 ){
    if( vfsFlags & SQLITE_OPEN_SHAREDCACHE ){
      int nFullPathname = pVfs->mxPathname+1;
      char *zFullPathname = sqlite3Malloc(nFullPathname);
      MUTEX_LOGIC( sqlite3_mutex *mutexShared; )
      p->sharable = 1;
      if( !zFullPathname ){
        sqlite3_free(p);
        return SQLITE_NOMEM;
      }
      sqlite3OsFullPathname(pVfs, zFilename, nFullPathname, zFullPathname);
#if SQLITE_THREADSAFE
      mutexOpen = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_OPEN);
      sqlite3_mutex_enter(mutexOpen);
      mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
      sqlite3_mutex_enter(mutexShared);
#endif
      for(pBt=GLOBAL(BtShared*,sqlite3SharedCacheList); pBt; pBt=pBt->pNext){
        assert( pBt->nRef>0 );
        if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager))
                 && sqlite3PagerVfs(pBt->pPager)==pVfs ){
          int iDb;
          for(iDb=db->nDb-1; iDb>=0; iDb--){
            Btree *pExisting = db->aDb[iDb].pBt;
................................................................................
    pBt->usableSize = pBt->pageSize - nReserve;
    assert( (pBt->pageSize & 7)==0 );  /* 8-byte alignment of pageSize */
   
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
    /* Add the new BtShared object to the linked list sharable BtShareds.
    */
    if( p->sharable ){
      MUTEX_LOGIC( sqlite3_mutex *mutexShared; )
      pBt->nRef = 1;
      MUTEX_LOGIC( mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);)
      if( SQLITE_THREADSAFE && sqlite3GlobalConfig.bCoreMutex ){
        pBt->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_FAST);
        if( pBt->mutex==0 ){
          rc = SQLITE_NOMEM;
          db->mallocFailed = 0;
          goto btree_open_out;
        }
................................................................................
** Decrement the BtShared.nRef counter.  When it reaches zero,
** remove the BtShared structure from the sharing list.  Return
** true if the BtShared.nRef counter reaches zero and return
** false if it is still positive.
*/
static int removeFromSharingList(BtShared *pBt){
#ifndef SQLITE_OMIT_SHARED_CACHE
  MUTEX_LOGIC( sqlite3_mutex *pMaster; )
  BtShared *pList;
  int removed = 0;

  assert( sqlite3_mutex_notheld(pBt->mutex) );
  MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
  sqlite3_mutex_enter(pMaster);
  pBt->nRef--;
  if( pBt->nRef<=0 ){
    if( GLOBAL(BtShared*,sqlite3SharedCacheList)==pBt ){
      GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt->pNext;
    }else{
      pList = GLOBAL(BtShared*,sqlite3SharedCacheList);
................................................................................
#endif
          rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
        offset -= ovflSize;
      }else{
        /* Need to read this page properly. It contains some of the
        ** range of data that is being read (eOp==0) or written (eOp!=0).
        */
#ifdef SQLITE_DIRECT_OVERFLOW_READ
        sqlite3_file *fd;
#endif
        int a = amt;
        if( a + offset > ovflSize ){
          a = ovflSize - offset;
        }

#ifdef SQLITE_DIRECT_OVERFLOW_READ
        /* If all the following are true:
        **
        **   1) this is a read operation, and 
        **   2) data is required from the start of this overflow page, and
        **   3) the database is file-backed, and
        **   4) there is no open write-transaction, and
        **   5) the database is not a WAL database,
        **
        ** then data can be read directly from the database file into the
        ** output buffer, bypassing the page-cache altogether. This speeds
        ** up loading large records that span many overflow pages.
        */
        if( eOp==0                                             /* (1) */
         && offset==0                                          /* (2) */
         && pBt->inTransaction==TRANS_READ                     /* (4) */
         && (fd = sqlite3PagerFile(pBt->pPager))->pMethods     /* (3) */
         && pBt->pPage1->aData[19]==0x01                       /* (5) */
        ){
          u8 aSave[4];
          u8 *aWrite = &pBuf[-4];
          memcpy(aSave, aWrite, 4);
          rc = sqlite3OsRead(fd, aWrite, a+4, pBt->pageSize * (nextPage-1));
          nextPage = get4byte(aWrite);
          memcpy(aWrite, aSave, 4);
        }else
#endif

        {
          DbPage *pDbPage;
          rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage);
          if( rc==SQLITE_OK ){
            aPayload = sqlite3PagerGetData(pDbPage);
            nextPage = get4byte(aPayload);



            rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
            sqlite3PagerUnref(pDbPage);
            offset = 0;
          }
        }
        amt -= a;
        pBuf += a;

      }
    }
  }

  if( rc==SQLITE_OK && amt>0 ){
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
          c = sqlite3VdbeRecordCompare(nCell, pCellKey, pIdxKey);
          sqlite3_free(pCellKey);
        }
      }
      if( c==0 ){
        if( pPage->intKey && !pPage->leaf ){
          lwr = idx;

          break;
        }else{
          *pRes = 0;
          rc = SQLITE_OK;
          goto moveto_finish;
        }
      }
................................................................................
        upr = idx-1;
      }
      if( lwr>upr ){
        break;
      }
      pCur->aiIdx[pCur->iPage] = (u16)(idx = (lwr+upr)/2);
    }
    assert( lwr==upr+1 || (pPage->intKey && !pPage->leaf) );
    assert( pPage->isInit );
    if( pPage->leaf ){
      chldPg = 0;
    }else if( lwr>=pPage->nCell ){
      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    }else{
      chldPg = get4byte(findCell(pPage, lwr));
................................................................................
      }else{
        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }
      assert( pTrunk!=0 );
      assert( pTrunk->aData!=0 );

      k = get4byte(&pTrunk->aData[4]); /* # of leaves on this trunk page */
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
................................................................................
      /* Drop the cell from the parent page. apDiv[i] still points to
      ** the cell within the parent, even though it has been dropped.
      ** This is safe because dropping a cell only overwrites the first
      ** four bytes of it, and this function does not need the first
      ** four bytes of the divider cell. So the pointer is safe to use
      ** later on.  
      **
      ** But not if we are in secure-delete mode. In secure-delete mode,
      ** the dropCell() routine will overwrite the entire cell with zeroes.
      ** In this case, temporarily copy the cell into the aOvflSpace[]
      ** buffer. It will be copied out again as soon as the aSpace[] buffer
      ** is allocated.  */
      if( pBt->secureDelete ){
        int iOff;

        iOff = SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent->aData);
        if( (iOff+szNew[i])>(int)pBt->usableSize ){
          rc = SQLITE_CORRUPT_BKPT;
          memset(apOld, 0, (i+1)*sizeof(MemPage*));
          goto balance_cleanup;
        }else{
          memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
          apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
................................................................................
    k = 0;                             /* Current 'new' sibling page */
    for(i=0; i<nCell; i++){
      int isDivider = 0;
      while( i==iNextOld ){
        /* Cell i is the cell immediately following the last cell on old
        ** sibling page j. If the siblings are not leaf pages of an
        ** intkey b-tree, then cell i was a divider cell. */
        assert( j+1 < ArraySize(apCopy) );
        pOld = apCopy[++j];
        iNextOld = i + !leafData + pOld->nCell + pOld->nOverflow;
        if( pOld->nOverflow ){
          nOverflow = pOld->nOverflow;
          iOverflow = i + !leafData + pOld->aOvfl[0].idx;
        }
        isDivider = !leafData;  
................................................................................
}

/*
** Release all resources associated with an sqlite3_backup* handle.
*/
SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p){
  sqlite3_backup **pp;                 /* Ptr to head of pagers backup list */
  MUTEX_LOGIC( sqlite3_mutex *mutex; ) /* Mutex to protect source database */
  int rc;                              /* Value to return */

  /* Enter the mutexes */
  if( p==0 ) return SQLITE_OK;
  sqlite3_mutex_enter(p->pSrcDb->mutex);
  sqlite3BtreeEnter(p->pSrc);
  MUTEX_LOGIC( mutex = p->pSrcDb->mutex; )
  if( p->pDestDb ){
    sqlite3_mutex_enter(p->pDestDb->mutex);
  }

  /* Detach this backup from the source pager. */
  if( p->pDestDb ){
    p->pSrc->nBackup--;
................................................................................
**
** The size of file pTo may be reduced by this operation. If anything 
** goes wrong, the transaction on pTo is rolled back. If successful, the 
** transaction is committed before returning.
*/
SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
  int rc;
  sqlite3_file *pFd;              /* File descriptor for database pTo */
  sqlite3_backup b;
  sqlite3BtreeEnter(pTo);
  sqlite3BtreeEnter(pFrom);

  assert( sqlite3BtreeIsInTrans(pTo) );
  pFd = sqlite3PagerFile(sqlite3BtreePager(pTo));
  if( pFd->pMethods ){
    i64 nByte = sqlite3BtreeGetPageSize(pFrom)*(i64)sqlite3BtreeLastPage(pFrom);
    sqlite3OsFileControl(pFd, SQLITE_FCNTL_OVERWRITE, &nByte);
  }

  /* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
  ** to 0. This is used by the implementations of sqlite3_backup_step()
  ** and sqlite3_backup_finish() to detect that they are being called
  ** from this function, not directly by the user.
  */
  memset(&b, 0, sizeof(b));
................................................................................
  ** or an error code.
  */
  sqlite3_backup_step(&b, 0x7FFFFFFF);
  assert( b.rc!=SQLITE_OK );
  rc = sqlite3_backup_finish(&b);
  if( rc==SQLITE_OK ){
    pTo->pBt->pageSizeFixed = 0;
  }else{
    sqlite3PagerClearCache(sqlite3BtreePager(b.pDest));
  }

  assert( sqlite3BtreeIsInTrans(pTo)==0 );
  sqlite3BtreeLeave(pFrom);
  sqlite3BtreeLeave(pTo);
  return rc;
}
#endif /* SQLITE_OMIT_VACUUM */

/************** End of backup.c **********************************************/
................................................................................

  if( !pExpr ){
    *ppVal = 0;
    return SQLITE_OK;
  }
  op = pExpr->op;

  /* op can only be TK_REGISTER if we have compiled with SQLITE_ENABLE_STAT3.
  ** The ifdef here is to enable us to achieve 100% branch test coverage even
  ** when SQLITE_ENABLE_STAT3 is omitted.
  */
#ifdef SQLITE_ENABLE_STAT3
  if( op==TK_REGISTER ) op = pExpr->op2;
#else
  if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
#endif

  /* Handle negative integers in a single step.  This is needed in the
  ** case when the value is -9223372036854775808.
................................................................................
}

/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){
  assert( addr>=0 || p->db->mallocFailed );
  if( addr>=0 ) sqlite3VdbeChangeP2(p, addr, p->nOp);
}


/*
** If the input FuncDef structure is ephemeral, then free it.  If
** the FuncDef is not ephermal, then do nothing.
*/
................................................................................
#ifndef NDEBUG
/*
** Change the comment on the the most recently coded instruction.  Or
** insert a No-op and add the comment to that new instruction.  This
** makes the code easier to read during debugging.  None of this happens
** in a production build.
*/
static void vdbeVComment(Vdbe *p, const char *zFormat, va_list ap){


  assert( p->nOp>0 || p->aOp==0 );
  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
  if( p->nOp ){
    assert( p->aOp );
    sqlite3DbFree(p->db, p->aOp[p->nOp-1].zComment);
    p->aOp[p->nOp-1].zComment = sqlite3VMPrintf(p->db, zFormat, ap);
  }
}
SQLITE_PRIVATE void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
  va_list ap;
  if( p ){
    va_start(ap, zFormat);

    vdbeVComment(p, zFormat, ap);
    va_end(ap);
  }
}
SQLITE_PRIVATE void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
  va_list ap;
  if( p ){
    sqlite3VdbeAddOp0(p, OP_Noop);




    va_start(ap, zFormat);

    vdbeVComment(p, zFormat, ap);
    va_end(ap);
  }
}
#endif  /* NDEBUG */

/*
** Return the opcode for a given address.  If the address is -1, then
................................................................................
  int nRow;                            /* Stop when row count reaches this */
  int nSub = 0;                        /* Number of sub-vdbes seen so far */
  SubProgram **apSub = 0;              /* Array of sub-vdbes */
  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
  sqlite3 *db = p->db;                 /* The database connection */
  int i;                               /* Loop counter */
  int rc = SQLITE_OK;                  /* Return code */
  Mem *pMem = &p->aMem[1];             /* First Mem of result set */

  assert( p->explain );
  assert( p->magic==VDBE_MAGIC_RUN );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );

  /* Even though this opcode does not use dynamic strings for
  ** the result, result columns may become dynamic if the user calls
  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
  */
  releaseMemArray(pMem, 8);
  p->pResultSet = 0;

  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */
    db->mallocFailed = 1;
    return SQLITE_ERROR;
  }
................................................................................
      {
        pMem->flags = MEM_Null;                       /* Comment */
        pMem->type = SQLITE_NULL;
      }
    }

    p->nResColumn = 8 - 4*(p->explain-1);
    p->pResultSet = &p->aMem[1];
    p->rc = SQLITE_OK;
    rc = SQLITE_ROW;
  }
  return rc;
}
#endif /* SQLITE_OMIT_EXPLAIN */

................................................................................
/*
** Each VDBE holds the result of the most recent sqlite3_step() call
** in p->rc.  This routine sets that result back to SQLITE_OK.
*/
SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe *p){
  p->rc = SQLITE_OK;
}

/*
** Copy the error code and error message belonging to the VDBE passed
** as the first argument to its database handle (so that they will be 
** returned by calls to sqlite3_errcode() and sqlite3_errmsg()).
**
** This function does not clear the VDBE error code or message, just
** copies them to the database handle.
*/
SQLITE_PRIVATE int sqlite3VdbeTransferError(Vdbe *p){
  sqlite3 *db = p->db;
  int rc = p->rc;
  if( p->zErrMsg ){
    u8 mallocFailed = db->mallocFailed;
    sqlite3BeginBenignMalloc();
    sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
    sqlite3EndBenignMalloc();
    db->mallocFailed = mallocFailed;
    db->errCode = rc;
  }else{
    sqlite3Error(db, rc, 0);
  }
  return rc;
}

/*
** Clean up a VDBE after execution but do not delete the VDBE just yet.
** Write any error messages into *pzErrMsg.  Return the result code.
**
** After this routine is run, the VDBE should be ready to be executed
** again.
................................................................................

  /* If the VDBE has be run even partially, then transfer the error code
  ** and error message from the VDBE into the main database structure.  But
  ** if the VDBE has just been set to run but has not actually executed any
  ** instructions yet, leave the main database error information unchanged.
  */
  if( p->pc>=0 ){
    sqlite3VdbeTransferError(p);




    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = 0;





    if( p->runOnlyOnce ) p->expired = 1;
  }else if( p->rc && p->expired ){
    /* The expired flag was set on the VDBE before the first call
    ** to sqlite3_step(). For consistency (since sqlite3_step() was
    ** called), set the database error in this case as well.
    */
    sqlite3Error(db, p->rc, 0);
................................................................................

  /* Get the size of the index entry.  Only indices entries of less
  ** than 2GiB are support - anything large must be database corruption.
  ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
  ** this code can safely assume that nCellKey is 32-bits  
  */
  assert( sqlite3BtreeCursorIsValid(pCur) );
  VVA_ONLY(rc =) sqlite3BtreeKeySize(pCur, &nCellKey);
  assert( rc==SQLITE_OK );     /* pCur is always valid so KeySize cannot fail */
  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );

  /* Read in the complete content of the index entry */
  memset(&m, 0, sizeof(m));
  rc = sqlite3VdbeMemFromBtree(pCur, 0, (int)nCellKey, 1, &m);
  if( rc ){
................................................................................
){
  i64 nCellKey = 0;
  int rc;
  BtCursor *pCur = pC->pCursor;
  Mem m;

  assert( sqlite3BtreeCursorIsValid(pCur) );
  VVA_ONLY(rc =) sqlite3BtreeKeySize(pCur, &nCellKey);
  assert( rc==SQLITE_OK );    /* pCur is always valid so KeySize cannot fail */
  /* nCellKey will always be between 0 and 0xffffffff because of the say
  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
  if( nCellKey<=0 || nCellKey>0x7fffffff ){
    *res = 0;
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
  );
  assert( p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE );
  if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
    /* If this statement was prepared using sqlite3_prepare_v2(), and an
    ** error has occured, then return the error code in p->rc to the
    ** caller. Set the error code in the database handle to the same value.
    */ 
    rc = sqlite3VdbeTransferError(p);
  }
  return (rc&db->errMask);
}

/*
** The maximum number of times that a statement will try to reparse
** itself before giving up and returning SQLITE_SCHEMA.
................................................................................
    if( u.am.pC->nullRow ){
      u.am.payloadSize = 0;
    }else if( u.am.pC->cacheStatus==p->cacheCtr ){
      u.am.payloadSize = u.am.pC->payloadSize;
      u.am.zRec = (char*)u.am.pC->aRow;
    }else if( u.am.pC->isIndex ){
      assert( sqlite3BtreeCursorIsValid(u.am.pCrsr) );
      VVA_ONLY(rc =) sqlite3BtreeKeySize(u.am.pCrsr, &u.am.payloadSize64);
      assert( rc==SQLITE_OK );   /* True because of CursorMoveto() call above */
      /* sqlite3BtreeParseCellPtr() uses getVarint32() to extract the
      ** payload size, so it is impossible for u.am.payloadSize64 to be
      ** larger than 32 bits. */
      assert( (u.am.payloadSize64 & SQLITE_MAX_U32)==(u64)u.am.payloadSize64 );
      u.am.payloadSize = (u32)u.am.payloadSize64;
    }else{
      assert( sqlite3BtreeCursorIsValid(u.am.pCrsr) );
      VVA_ONLY(rc =) sqlite3BtreeDataSize(u.am.pCrsr, &u.am.payloadSize);
      assert( rc==SQLITE_OK );   /* DataSize() cannot fail */
    }
  }else if( ALWAYS(u.am.pC->pseudoTableReg>0) ){
    u.am.pReg = &aMem[u.am.pC->pseudoTableReg];
    assert( u.am.pReg->flags & MEM_Blob );
    assert( memIsValid(u.am.pReg) );
    u.am.payloadSize = u.am.pReg->n;
................................................................................
  */
  assert( u.bk.pC->deferredMoveto==0 );
  rc = sqlite3VdbeCursorMoveto(u.bk.pC);
  if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;

  if( u.bk.pC->isIndex ){
    assert( !u.bk.pC->isTable );
    VVA_ONLY(rc =) sqlite3BtreeKeySize(u.bk.pCrsr, &u.bk.n64);
    assert( rc==SQLITE_OK );    /* True because of CursorMoveto() call above */
    if( u.bk.n64>db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
    u.bk.n = (u32)u.bk.n64;
  }else{
    VVA_ONLY(rc =) sqlite3BtreeDataSize(u.bk.pCrsr, &u.bk.n);
    assert( rc==SQLITE_OK );    /* DataSize() cannot fail */
    if( u.bk.n>(u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
  }
  if( sqlite3VdbeMemGrow(pOut, u.bk.n, 0) ){
    goto no_mem;
................................................................................
  int res;
#endif /* local variables moved into u.bn */

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  u.bn.pC = p->apCsr[pOp->p1];
  assert( u.bn.pC!=0 );
  u.bn.pCrsr = u.bn.pC->pCursor;

  u.bn.res = 0;

  if( ALWAYS(u.bn.pCrsr!=0) ){
    rc = sqlite3BtreeLast(u.bn.pCrsr, &u.bn.res);
  }
  u.bn.pC->nullRow = (u8)u.bn.res;
  u.bn.pC->deferredMoveto = 0;
  u.bn.pC->rowidIsValid = 0;
  u.bn.pC->cacheStatus = CACHE_STALE;
  if( pOp->p2>0 && u.bn.res ){
................................................................................
#ifndef SQLITE_OMIT_WAL
  u.ch.zFilename = sqlite3PagerFilename(u.ch.pPager);

  /* Do not allow a transition to journal_mode=WAL for a database
  ** in temporary storage or if the VFS does not support shared memory
  */
  if( u.ch.eNew==PAGER_JOURNALMODE_WAL
   && (sqlite3Strlen30(u.ch.zFilename)==0           /* Temp file */
       || !sqlite3PagerWalSupported(u.ch.pPager))   /* No shared-memory support */
  ){
    u.ch.eNew = u.ch.eOld;
  }

  if( (u.ch.eNew!=u.ch.eOld)
   && (u.ch.eOld==PAGER_JOURNALMODE_WAL || u.ch.eNew==PAGER_JOURNALMODE_WAL)
................................................................................

  u.co.pVtab = pOp->p4.pVtab->pVtab;
  u.co.pName = &aMem[pOp->p1];
  assert( u.co.pVtab->pModule->xRename );
  assert( memIsValid(u.co.pName) );
  REGISTER_TRACE(pOp->p1, u.co.pName);
  assert( u.co.pName->flags & MEM_Str );
  testcase( u.co.pName->enc==SQLITE_UTF8 );
  testcase( u.co.pName->enc==SQLITE_UTF16BE );
  testcase( u.co.pName->enc==SQLITE_UTF16LE );
  rc = sqlite3VdbeChangeEncoding(u.co.pName, SQLITE_UTF8);
  if( rc==SQLITE_OK ){
    rc = u.co.pVtab->pModule->xRename(u.co.pVtab, u.co.pName->z);
    importVtabErrMsg(p, u.co.pVtab);
    p->expired = 0;
  }
  break;
}
#endif

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VUpdate P1 P2 P3 P4 *
**
................................................................................
  ** allowing it to be repopulated by the memcpy() on the following line.
  */
  ExprSetProperty(pExpr, EP_Static);
  sqlite3ExprDelete(db, pExpr);
  memcpy(pExpr, pDup, sizeof(*pExpr));
  sqlite3DbFree(db, pDup);
}


/*
** Return TRUE if the name zCol occurs anywhere in the USING clause.
**
** Return FALSE if the USING clause is NULL or if it does not contain
** zCol.
*/
static int nameInUsingClause(IdList *pUsing, const char *zCol){
  if( pUsing ){
    int k;
    for(k=0; k<pUsing->nId; k++){
      if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ) return 1;
    }
  }
  return 0;
}


/*
** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
** that name in the set of source tables in pSrcList and make the pExpr 
** expression node refer back to that source column.  The following changes
** are made to pExpr:
**
................................................................................
          pExpr->iTable = pItem->iCursor;
          pExpr->pTab = pTab;
          pSchema = pTab->pSchema;
          pMatch = pItem;
        }
        for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
          if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
            /* If there has been exactly one prior match and this match
            ** is for the right-hand table of a NATURAL JOIN or is in a 
            ** USING clause, then skip this match.
            */
            if( cnt==1 ){
              if( pItem->jointype & JT_NATURAL ) continue;
              if( nameInUsingClause(pItem->pUsing, zCol) ) continue;
            }
            cnt++;
            pExpr->iTable = pItem->iCursor;
            pExpr->pTab = pTab;
            pMatch = pItem;
            pSchema = pTab->pSchema;
            /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
            pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;




















            break;
          }
        }
      }
    }

#ifndef SQLITE_OMIT_TRIGGER
................................................................................
    if( pToken ){
      if( nExtra==0 ){
        pNew->flags |= EP_IntValue;
        pNew->u.iValue = iValue;
      }else{
        int c;
        pNew->u.zToken = (char*)&pNew[1];
        assert( pToken->z!=0 || pToken->n==0 );
        if( pToken->n ) memcpy(pNew->u.zToken, pToken->z, pToken->n);
        pNew->u.zToken[pToken->n] = 0;
        if( dequote && nExtra>=3 
             && ((c = pToken->z[0])=='\'' || c=='"' || c=='[' || c=='`') ){
          sqlite3Dequote(pNew->u.zToken);
          if( c=='"' ) pNew->flags |= EP_DblQuoted;
        }
      }
................................................................................
  /* Check to see if an existing table or index can be used to
  ** satisfy the query.  This is preferable to generating a new 
  ** ephemeral table.
  */
  p = (ExprHasProperty(pX, EP_xIsSelect) ? pX->x.pSelect : 0);
  if( ALWAYS(pParse->nErr==0) && isCandidateForInOpt(p) ){
    sqlite3 *db = pParse->db;              /* Database connection */


    Vdbe *v = sqlite3GetVdbe(pParse);      /* Virtual machine being coded */
    Table *pTab;                           /* Table <table>. */
    Expr *pExpr;                           /* Expression <column> */
    int iCol;                              /* Index of column <column> */
    int iDb;                               /* Database idx for pTab */

    assert( p );                        /* Because of isCandidateForInOpt(p) */
    assert( p->pEList!=0 );             /* Because of isCandidateForInOpt(p) */
    assert( p->pEList->a[0].pExpr!=0 ); /* Because of isCandidateForInOpt(p) */
    assert( p->pSrc!=0 );               /* Because of isCandidateForInOpt(p) */
    pTab = p->pSrc->a[0].pTab;
    pExpr = p->pEList->a[0].pExpr;
    iCol = pExpr->iColumn;
   
    /* Code an OP_VerifyCookie and OP_TableLock for <table>. */
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    sqlite3CodeVerifySchema(pParse, iDb);
    sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

    /* This function is only called from two places. In both cases the vdbe
................................................................................
  if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 2;
  if( ExprHasProperty(pA, EP_IntValue) ){
    if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){
      return 2;
    }
  }else if( pA->op!=TK_COLUMN && pA->u.zToken ){
    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 2;
    if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
      return 2;
    }
  }
  if( (pA->flags & EP_ExpCollate)!=(pB->flags & EP_ExpCollate) ) return 1;
  if( (pA->flags & EP_ExpCollate)!=0 && pA->pColl!=pB->pColl ) return 2;
  return 0;
}
................................................................................
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code associated with the ANALYZE command.
**
** The ANALYZE command gather statistics about the content of tables
** and indices.  These statistics are made available to the query planner
** to help it make better decisions about how to perform queries.
**
** The following system tables are or have been supported:
**
**    CREATE TABLE sqlite_stat1(tbl, idx, stat);
**    CREATE TABLE sqlite_stat2(tbl, idx, sampleno, sample);
**    CREATE TABLE sqlite_stat3(tbl, idx, nEq, nLt, nDLt, sample);
**
** Additional tables might be added in future releases of SQLite.
** The sqlite_stat2 table is not created or used unless the SQLite version
** is between 3.6.18 and 3.7.8, inclusive, and unless SQLite is compiled
** with SQLITE_ENABLE_STAT2.  The sqlite_stat2 table is deprecated.
** The sqlite_stat2 table is superceded by sqlite_stat3, which is only
** created and used by SQLite versions 3.7.9 and later and with
** SQLITE_ENABLE_STAT3 defined.  The fucntionality of sqlite_stat3
** is a superset of sqlite_stat2.  
**
** Format of sqlite_stat1:
**
** There is normally one row per index, with the index identified by the
** name in the idx column.  The tbl column is the name of the table to
** which the index belongs.  In each such row, the stat column will be
** a string consisting of a list of integers.  The first integer in this
** list is the number of rows in the index and in the table.  The second
** integer is the average number of rows in the index that have the same
** value in the first column of the index.  The third integer is the average
** number of rows in the index that have the same value for the first two
** columns.  The N-th integer (for N>1) is the average number of rows in 
** the index which have the same value for the first N-1 columns.  For
** a K-column index, there will be K+1 integers in the stat column.  If
** the index is unique, then the last integer will be 1.
**
** The list of integers in the stat column can optionally be followed
** by the keyword "unordered".  The "unordered" keyword, if it is present,
** must be separated from the last integer by a single space.  If the
** "unordered" keyword is present, then the query planner assumes that
** the index is unordered and will not use the index for a range query.
** 
** If the sqlite_stat1.idx column is NULL, then the sqlite_stat1.stat
** column contains a single integer which is the (estimated) number of
** rows in the table identified by sqlite_stat1.tbl.
**
** Format of sqlite_stat2:
**
** The sqlite_stat2 is only created and is only used if SQLite is compiled
** with SQLITE_ENABLE_STAT2 and if the SQLite version number is between
** 3.6.18 and 3.7.8.  The "stat2" table contains additional information
** about the distribution of keys within an index.  The index is identified by
** the "idx" column and the "tbl" column is the name of the table to which
** the index belongs.  There are usually 10 rows in the sqlite_stat2
** table for each index.
**
** The sqlite_stat2 entries for an index that have sampleno between 0 and 9
** inclusive are samples of the left-most key value in the index taken at
** evenly spaced points along the index.  Let the number of samples be S
** (10 in the standard build) and let C be the number of rows in the index.
** Then the sampled rows are given by:
**
**     rownumber = (i*C*2 + C)/(S*2)
**
** For i between 0 and S-1.  Conceptually, the index space is divided into
** S uniform buckets and the samples are the middle row from each bucket.
**
** The format for sqlite_stat2 is recorded here for legacy reference.  This
** version of SQLite does not support sqlite_stat2.  It neither reads nor
** writes the sqlite_stat2 table.  This version of SQLite only supports
** sqlite_stat3.
**
** Format for sqlite_stat3:
**
** The sqlite_stat3 is an enhancement to sqlite_stat2.  A new name is
** used to avoid compatibility problems.  
**
** The format of the sqlite_stat3 table is similar to the format of
** the sqlite_stat2 table.  There are multiple entries for each index.
** The idx column names the index and the tbl column is the table of the
** index.  If the idx and tbl columns are the same, then the sample is
** of the INTEGER PRIMARY KEY.  The sample column is a value taken from
** the left-most column of the index.  The nEq column is the approximate
** number of entires in the index whose left-most column exactly matches
** the sample.  nLt is the approximate number of entires whose left-most
** column is less than the sample.  The nDLt column is the approximate
** number of distinct left-most entries in the index that are less than
** the sample.
**
** Future versions of SQLite might change to store a string containing
** multiple integers values in the nDLt column of sqlite_stat3.  The first
** integer will be the number of prior index entires that are distinct in
** the left-most column.  The second integer will be the number of prior index
** entries that are distinct in the first two columns.  The third integer
** will be the number of prior index entries that are distinct in the first
** three columns.  And so forth.  With that extension, the nDLt field is
** similar in function to the sqlite_stat1.stat field.
**
** There can be an arbitrary number of sqlite_stat3 entries per index.
** The ANALYZE command will typically generate sqlite_stat3 tables
** that contain between 10 and 40 samples which are distributed across
** the key space, though not uniformly, and which include samples with
** largest possible nEq values.
*/
#ifndef SQLITE_OMIT_ANALYZE

/*
** This routine generates code that opens the sqlite_stat1 table for
** writing with cursor iStatCur. If the library was built with the
** SQLITE_ENABLE_STAT3 macro defined, then the sqlite_stat3 table is
** opened for writing using cursor (iStatCur+1)
**
** If the sqlite_stat1 tables does not previously exist, it is created.
** Similarly, if the sqlite_stat3 table does not exist and the library
** is compiled with SQLITE_ENABLE_STAT3 defined, it is created. 
**
** Argument zWhere may be a pointer to a buffer containing a table name,
** or it may be a NULL pointer. If it is not NULL, then all entries in
** the sqlite_stat1 and (if applicable) sqlite_stat3 tables associated
** with the named table are deleted. If zWhere==0, then code is generated
** to delete all stat table entries.
*/
static void openStatTable(
  Parse *pParse,          /* Parsing context */
  int iDb,                /* The database we are looking in */
  int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
................................................................................
  const char *zWhereType  /* Either "tbl" or "idx" */
){
  static const struct {
    const char *zName;
    const char *zCols;
  } aTable[] = {
    { "sqlite_stat1", "tbl,idx,stat" },
#ifdef SQLITE_ENABLE_STAT3
    { "sqlite_stat3", "tbl,idx,neq,nlt,ndlt,sample" },
#endif
  };

  int aRoot[] = {0, 0};
  u8 aCreateTbl[] = {0, 0};

  int i;
................................................................................
  Db *pDb;
  Vdbe *v = sqlite3GetVdbe(pParse);
  if( v==0 ) return;
  assert( sqlite3BtreeHoldsAllMutexes(db) );
  assert( sqlite3VdbeDb(v)==db );
  pDb = &db->aDb[iDb];

  /* Create new statistic tables if they do not exist, or clear them
  ** if they do already exist.
  */
  for(i=0; i<ArraySize(aTable); i++){
    const char *zTab = aTable[i].zName;
    Table *pStat;
    if( (pStat = sqlite3FindTable(db, zTab, pDb->zName))==0 ){
      /* The sqlite_stat[12] table does not exist. Create it. Note that a 
      ** side-effect of the CREATE TABLE statement is to leave the rootpage 
      ** of the new table in register pParse->regRoot. This is important 
................................................................................
      }else{
        /* The sqlite_stat[12] table already exists.  Delete all rows. */
        sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
      }
    }
  }

  /* Open the sqlite_stat[13] tables for writing. */
  for(i=0; i<ArraySize(aTable); i++){
    sqlite3VdbeAddOp3(v, OP_OpenWrite, iStatCur+i, aRoot[i], iDb);
    sqlite3VdbeChangeP4(v, -1, (char *)3, P4_INT32);
    sqlite3VdbeChangeP5(v, aCreateTbl[i]);
  }
}

/*
** Recommended number of samples for sqlite_stat3
*/
#ifndef SQLITE_STAT3_SAMPLES
# define SQLITE_STAT3_SAMPLES 24
#endif

/*
** Three SQL functions - stat3_init(), stat3_push(), and stat3_pop() -
** share an instance of the following structure to hold their state
** information.
*/
typedef struct Stat3Accum Stat3Accum;
struct Stat3Accum {
  tRowcnt nRow;             /* Number of rows in the entire table */
  tRowcnt nPSample;         /* How often to do a periodic sample */
  int iMin;                 /* Index of entry with minimum nEq and hash */
  int mxSample;             /* Maximum number of samples to accumulate */
  int nSample;              /* Current number of samples */
  u32 iPrn;                 /* Pseudo-random number used for sampling */
  struct Stat3Sample {
    i64 iRowid;                /* Rowid in main table of the key */
    tRowcnt nEq;               /* sqlite_stat3.nEq */
    tRowcnt nLt;               /* sqlite_stat3.nLt */
    tRowcnt nDLt;              /* sqlite_stat3.nDLt */
    u8 isPSample;              /* True if a periodic sample */
    u32 iHash;                 /* Tiebreaker hash */
  } *a;                     /* An array of samples */
};

#ifdef SQLITE_ENABLE_STAT3
/*
** Implementation of the stat3_init(C,S) SQL function.  The two parameters
** are the number of rows in the table or index (C) and the number of samples
** to accumulate (S).
**
** This routine allocates the Stat3Accum object.
**
** The return value is the Stat3Accum object (P).
*/
static void stat3Init(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  Stat3Accum *p;
  tRowcnt nRow;
  int mxSample;
  int n;

  UNUSED_PARAMETER(argc);
  nRow = (tRowcnt)sqlite3_value_int64(argv[0]);
  mxSample = sqlite3_value_int(argv[1]);
  n = sizeof(*p) + sizeof(p->a[0])*mxSample;
  p = sqlite3_malloc( n );
  if( p==0 ){
    sqlite3_result_error_nomem(context);
    return;
  }
  memset(p, 0, n);
  p->a = (struct Stat3Sample*)&p[1];
  p->nRow = nRow;
  p->mxSample = mxSample;
  p->nPSample = p->nRow/(mxSample/3+1) + 1;
  sqlite3_randomness(sizeof(p->iPrn), &p->iPrn);
  sqlite3_result_blob(context, p, sizeof(p), sqlite3_free);
}
static const FuncDef stat3InitFuncdef = {
  2,                /* nArg */
  SQLITE_UTF8,      /* iPrefEnc */
  0,                /* flags */
  0,                /* pUserData */
  0,                /* pNext */
  stat3Init,        /* xFunc */
  0,                /* xStep */
  0,                /* xFinalize */
  "stat3_init",     /* zName */
  0,                /* pHash */
  0                 /* pDestructor */
};


/*
** Implementation of the stat3_push(nEq,nLt,nDLt,rowid,P) SQL function.  The
** arguments describe a single key instance.  This routine makes the 
** decision about whether or not to retain this key for the sqlite_stat3
** table.
**
** The return value is NULL.
*/
static void stat3Push(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  Stat3Accum *p = (Stat3Accum*)sqlite3_value_blob(argv[4]);
  tRowcnt nEq = sqlite3_value_int64(argv[0]);
  tRowcnt nLt = sqlite3_value_int64(argv[1]);
  tRowcnt nDLt = sqlite3_value_int64(argv[2]);
  i64 rowid = sqlite3_value_int64(argv[3]);
  u8 isPSample = 0;
  u8 doInsert = 0;
  int iMin = p->iMin;
  struct Stat3Sample *pSample;
  int i;
  u32 h;

  UNUSED_PARAMETER(context);
  UNUSED_PARAMETER(argc);
  if( nEq==0 ) return;
  h = p->iPrn = p->iPrn*1103515245 + 12345;
  if( (nLt/p->nPSample)!=((nEq+nLt)/p->nPSample) ){
    doInsert = isPSample = 1;
  }else if( p->nSample<p->mxSample ){
    doInsert = 1;
  }else{
    if( nEq>p->a[iMin].nEq || (nEq==p->a[iMin].nEq && h>p->a[iMin].iHash) ){
      doInsert = 1;
    }
  }
  if( !doInsert ) return;
  if( p->nSample==p->mxSample ){
    assert( p->nSample - iMin - 1 >= 0 );
    memmove(&p->a[iMin], &p->a[iMin+1], sizeof(p->a[0])*(p->nSample-iMin-1));
    pSample = &p->a[p->nSample-1];
  }else{
    pSample = &p->a[p->nSample++];
  }
  pSample->iRowid = rowid;
  pSample->nEq = nEq;
  pSample->nLt = nLt;
  pSample->nDLt = nDLt;
  pSample->iHash = h;
  pSample->isPSample = isPSample;

  /* Find the new minimum */
  if( p->nSample==p->mxSample ){
    pSample = p->a;
    i = 0;
    while( pSample->isPSample ){
      i++;
      pSample++;
      assert( i<p->nSample );
    }
    nEq = pSample->nEq;
    h = pSample->iHash;
    iMin = i;
    for(i++, pSample++; i<p->nSample; i++, pSample++){
      if( pSample->isPSample ) continue;
      if( pSample->nEq<nEq
       || (pSample->nEq==nEq && pSample->iHash<h)
      ){
        iMin = i;
        nEq = pSample->nEq;
        h = pSample->iHash;
      }
    }
    p->iMin = iMin;
  }
}
static const FuncDef stat3PushFuncdef = {
  5,                /* nArg */
  SQLITE_UTF8,      /* iPrefEnc */
  0,                /* flags */
  0,                /* pUserData */
  0,                /* pNext */
  stat3Push,        /* xFunc */
  0,                /* xStep */
  0,                /* xFinalize */
  "stat3_push",     /* zName */
  0,                /* pHash */
  0                 /* pDestructor */
};

/*
** Implementation of the stat3_get(P,N,...) SQL function.  This routine is
** used to query the results.  Content is returned for the Nth sqlite_stat3
** row where N is between 0 and S-1 and S is the number of samples.  The
** value returned depends on the number of arguments.
**
**   argc==2    result:  rowid
**   argc==3    result:  nEq
**   argc==4    result:  nLt
**   argc==5    result:  nDLt
*/
static void stat3Get(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  int n = sqlite3_value_int(argv[1]);
  Stat3Accum *p = (Stat3Accum*)sqlite3_value_blob(argv[0]);

  assert( p!=0 );
  if( p->nSample<=n ) return;
  switch( argc ){
    case 2:  sqlite3_result_int64(context, p->a[n].iRowid); break;
    case 3:  sqlite3_result_int64(context, p->a[n].nEq);    break;
    case 4:  sqlite3_result_int64(context, p->a[n].nLt);    break;
    default: sqlite3_result_int64(context, p->a[n].nDLt);   break;
  }
}
static const FuncDef stat3GetFuncdef = {
  -1,               /* nArg */
  SQLITE_UTF8,      /* iPrefEnc */
  0,                /* flags */
  0,                /* pUserData */
  0,                /* pNext */
  stat3Get,         /* xFunc */
  0,                /* xStep */
  0,                /* xFinalize */
  "stat3_get",     /* zName */
  0,                /* pHash */
  0                 /* pDestructor */
};
#endif /* SQLITE_ENABLE_STAT3 */




/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
................................................................................
  int i;                       /* Loop counter */
  int topOfLoop;               /* The top of the loop */
  int endOfLoop;               /* The end of the loop */
  int jZeroRows = -1;          /* Jump from here if number of rows is zero */
  int iDb;                     /* Index of database containing pTab */
  int regTabname = iMem++;     /* Register containing table name */
  int regIdxname = iMem++;     /* Register containing index name */
  int regStat1 = iMem++;       /* The stat column of sqlite_stat1 */
#ifdef SQLITE_ENABLE_STAT3
  int regNumEq = regStat1;     /* Number of instances.  Same as regStat1 */
  int regNumLt = iMem++;       /* Number of keys less than regSample */
  int regNumDLt = iMem++;      /* Number of distinct keys less than regSample */
  int regSample = iMem++;      /* The next sample value */
  int regRowid = regSample;    /* Rowid of a sample */
  int regAccum = iMem++;       /* Register to hold Stat3Accum object */
  int regLoop = iMem++;        /* Loop counter */
  int regCount = iMem++;       /* Number of rows in the table or index */
  int regTemp1 = iMem++;       /* Intermediate register */
  int regTemp2 = iMem++;       /* Intermediate register */
  int once = 1;                /* One-time initialization */
  int shortJump = 0;           /* Instruction address */
  int iTabCur = pParse->nTab++; /* Table cursor */
#endif
  int regCol = iMem++;         /* Content of a column in analyzed table */
  int regRec = iMem++;         /* Register holding completed record */
  int regTemp = iMem++;        /* Temporary use register */
  int regNewRowid = iMem++;    /* Rowid for the inserted record */










  v = sqlite3GetVdbe(pParse);
  if( v==0 || NEVER(pTab==0) ){
    return;
  }
  if( pTab->tnum==0 ){
    /* Do not gather statistics on views or virtual tables */
................................................................................
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

  iIdxCur = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol;
    KeyInfo *pKey;
    int addrIfNot = 0;           /* address of OP_IfNot */
    int *aChngAddr;              /* Array of jump instruction addresses */

    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
    VdbeNoopComment((v, "Begin analysis of %s", pIdx->zName));
    nCol = pIdx->nColumn;
    aChngAddr = sqlite3DbMallocRaw(db, sizeof(int)*nCol);
    if( aChngAddr==0 ) continue;
    pKey = sqlite3IndexKeyinfo(pParse, pIdx);
    if( iMem+1+(nCol*2)>pParse->nMem ){
      pParse->nMem = iMem+1+(nCol*2);
    }

    /* Open a cursor to the index to be analyzed. */
    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
................................................................................
    sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,
        (char *)pKey, P4_KEYINFO_HANDOFF);
    VdbeComment((v, "%s", pIdx->zName));

    /* Populate the register containing the index name. */
    sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, pIdx->zName, 0);

#ifdef SQLITE_ENABLE_STAT3

    if( once ){
      once = 0;
      sqlite3OpenTable(pParse, iTabCur, iDb, pTab, OP_OpenRead);





    }
    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regCount);
    sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_STAT3_SAMPLES, regTemp1);









    sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumEq);
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumLt);
    sqlite3VdbeAddOp2(v, OP_Integer, -1, regNumDLt);

    sqlite3VdbeAddOp4(v, OP_Function, 1, regCount, regAccum,
                      (char*)&stat3InitFuncdef, P4_FUNCDEF);
    sqlite3VdbeChangeP5(v, 2);
#endif /* SQLITE_ENABLE_STAT3 */

    /* The block of memory cells initialized here is used as follows.
    **
    **    iMem:                
    **        The total number of rows in the table.
    **
    **    iMem+1 .. iMem+nCol: 
................................................................................
    }

    /* Start the analysis loop. This loop runs through all the entries in
    ** the index b-tree.  */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);  /* Increment row counter */

    for(i=0; i<nCol; i++){
      CollSeq *pColl;
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
      if( i==0 ){































        /* Always record the very first row */
        addrIfNot = sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
      }
      assert( pIdx->azColl!=0 );
      assert( pIdx->azColl[i]!=0 );
      pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
      aChngAddr[i] = sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
                                      (char*)pColl, P4_COLLSEQ);
      sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
      VdbeComment((v, "jump if column %d changed", i));
#ifdef SQLITE_ENABLE_STAT3
      if( i==0 ){
        sqlite3VdbeAddOp2(v, OP_AddImm, regNumEq, 1);
        VdbeComment((v, "incr repeat count"));
      }





#endif
    }
    sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      sqlite3VdbeJumpHere(v, aChngAddr[i]);  /* Set jump dest for the OP_Ne */
      if( i==0 ){
        sqlite3VdbeJumpHere(v, addrIfNot);   /* Jump dest for OP_IfNot */
#ifdef SQLITE_ENABLE_STAT3
        sqlite3VdbeAddOp4(v, OP_Function, 1, regNumEq, regTemp2,
                          (char*)&stat3PushFuncdef, P4_FUNCDEF);
        sqlite3VdbeChangeP5(v, 5);
        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, pIdx->nColumn, regRowid);
        sqlite3VdbeAddOp3(v, OP_Add, regNumEq, regNumLt, regNumLt);
        sqlite3VdbeAddOp2(v, OP_AddImm, regNumDLt, 1);
        sqlite3VdbeAddOp2(v, OP_Integer, 1, regNumEq);
#endif        
      }

      sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);
    }
    sqlite3DbFree(db, aChngAddr);


    /* Always jump here after updating the iMem+1...iMem+1+nCol counters */
    sqlite3VdbeResolveLabel(v, endOfLoop);

    sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
#ifdef SQLITE_ENABLE_STAT3
    sqlite3VdbeAddOp4(v, OP_Function, 1, regNumEq, regTemp2,
                      (char*)&stat3PushFuncdef, P4_FUNCDEF);
    sqlite3VdbeChangeP5(v, 5);
    sqlite3VdbeAddOp2(v, OP_Integer, -1, regLoop);
    shortJump = 
    sqlite3VdbeAddOp2(v, OP_AddImm, regLoop, 1);
    sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regTemp1,
                      (char*)&stat3GetFuncdef, P4_FUNCDEF);
    sqlite3VdbeChangeP5(v, 2);
    sqlite3VdbeAddOp1(v, OP_IsNull, regTemp1);
    sqlite3VdbeAddOp3(v, OP_NotExists, iTabCur, shortJump, regTemp1);
    sqlite3VdbeAddOp3(v, OP_Column, iTabCur, pIdx->aiColumn[0], regSample);
    sqlite3ColumnDefault(v, pTab, pIdx->aiColumn[0], regSample);
    sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumEq,
                      (char*)&stat3GetFuncdef, P4_FUNCDEF);
    sqlite3VdbeChangeP5(v, 3);
    sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumLt,
                      (char*)&stat3GetFuncdef, P4_FUNCDEF);
    sqlite3VdbeChangeP5(v, 4);
    sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumDLt,
                      (char*)&stat3GetFuncdef, P4_FUNCDEF);
    sqlite3VdbeChangeP5(v, 5);
    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 6, regRec, "bbbbbb", 0);
    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regNewRowid);
    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regNewRowid);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, shortJump);
    sqlite3VdbeJumpHere(v, shortJump+2);
#endif        

    /* Store the results in sqlite_stat1.
    **
    ** The result is a single row of the sqlite_stat1 table.  The first
    ** two columns are the names of the table and index.  The third column
    ** is a string composed of a list of integer statistics about the
    ** index.  The first integer in the list is the total number of entries
................................................................................
    **
    **        I = (K+D-1)/D
    **
    ** If K==0 then no entry is made into the sqlite_stat1 table.  
    ** If K>0 then it is always the case the D>0 so division by zero
    ** is never possible.
    */
    sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regStat1);
    if( jZeroRows<0 ){
      jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regStat1, regStat1);
      sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
      sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
      sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);
      sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regStat1, regStat1);
    }
    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regNewRowid);
    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  }

  /* If the table has no indices, create a single sqlite_stat1 entry
  ** containing NULL as the index name and the row count as the content.
  */
  if( pTab->pIndex==0 ){
    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
    VdbeComment((v, "%s", pTab->zName));
    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat1);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1);
  }else{
    sqlite3VdbeJumpHere(v, jZeroRows);
    jZeroRows = sqlite3VdbeAddOp0(v, OP_Goto);
  }
  sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
  sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
  sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
  sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regNewRowid);
  sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  if( pParse->nMem<regRec ) pParse->nMem = regRec;
  sqlite3VdbeJumpHere(v, jZeroRows);
}


/*
** Generate code that will cause the most recent index analysis to
** be loaded into internal hash tables where is can be used.
*/
static void loadAnalysis(Parse *pParse, int iDb){
  Vdbe *v = sqlite3GetVdbe(pParse);
................................................................................
  Schema *pSchema = db->aDb[iDb].pSchema;    /* Schema of database iDb */
  HashElem *k;
  int iStatCur;
  int iMem;

  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab;
  pParse->nTab += 3;
  openStatTable(pParse, iDb, iStatCur, 0, 0);
  iMem = pParse->nMem+1;
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
    Table *pTab = (Table*)sqliteHashData(k);
    analyzeOneTable(pParse, pTab, 0, iStatCur, iMem);
  }
................................................................................
  int iStatCur;

  assert( pTab!=0 );
  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab;
  pParse->nTab += 3;
  if( pOnlyIdx ){
    openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx");
  }else{
    openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl");
  }
  analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur, pParse->nMem+1);
  loadAnalysis(pParse, iDb);
................................................................................
** the table.
*/
static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
  analysisInfo *pInfo = (analysisInfo*)pData;
  Index *pIndex;
  Table *pTable;
  int i, c, n;
  tRowcnt v;
  const char *z;

  assert( argc==3 );
  UNUSED_PARAMETER2(NotUsed, argc);

  if( argv==0 || argv[0]==0 || argv[2]==0 ){
    return 0;
................................................................................
}

/*
** If the Index.aSample variable is not NULL, delete the aSample[] array
** and its contents.
*/
SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){
#ifdef SQLITE_ENABLE_STAT3
  if( pIdx->aSample ){
    int j;
    for(j=0; j<pIdx->nSample; j++){
      IndexSample *p = &pIdx->aSample[j];
      if( p->eType==SQLITE_TEXT || p->eType==SQLITE_BLOB ){
        sqlite3DbFree(db, p->u.z);
      }
    }
    sqlite3DbFree(db, pIdx->aSample);
  }
  if( db && db->pnBytesFreed==0 ){
    pIdx->nSample = 0;
    pIdx->aSample = 0;
  }
#else
  UNUSED_PARAMETER(db);
  UNUSED_PARAMETER(pIdx);
#endif
}

#ifdef SQLITE_ENABLE_STAT3
/*
** Load content from the sqlite_stat3 table into the Index.aSample[]
** arrays of all indices.
*/
static int loadStat3(sqlite3 *db, const char *zDb){
  int rc;                       /* Result codes from subroutines */
  sqlite3_stmt *pStmt = 0;      /* An SQL statement being run */
  char *zSql;                   /* Text of the SQL statement */
  Index *pPrevIdx = 0;          /* Previous index in the loop */
  int idx = 0;                  /* slot in pIdx->aSample[] for next sample */
  int eType;                    /* Datatype of a sample */
  IndexSample *pSample;         /* A slot in pIdx->aSample[] */

  if( !sqlite3FindTable(db, "sqlite_stat3", zDb) ){
    return SQLITE_OK;
  }

  zSql = sqlite3MPrintf(db, 
      "SELECT idx,count(*) FROM %Q.sqlite_stat3"
      " GROUP BY idx", zDb);
  if( !zSql ){
    return SQLITE_NOMEM;
  }
  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
  sqlite3DbFree(db, zSql);
  if( rc ) return rc;

  while( sqlite3_step(pStmt)==SQLITE_ROW ){
    char *zIndex;   /* Index name */
    Index *pIdx;    /* Pointer to the index object */
    int nSample;    /* Number of samples */

    zIndex = (char *)sqlite3_column_text(pStmt, 0);
    if( zIndex==0 ) continue;
    nSample = sqlite3_column_int(pStmt, 1);
    pIdx = sqlite3FindIndex(db, zIndex, zDb);
    if( pIdx==0 ) continue;
    assert( pIdx->nSample==0 );
    pIdx->nSample = nSample;
    pIdx->aSample = sqlite3MallocZero( nSample*sizeof(IndexSample) );
    pIdx->avgEq = pIdx->aiRowEst[1];
    if( pIdx->aSample==0 ){
      db->mallocFailed = 1;
      sqlite3_finalize(pStmt);
      return SQLITE_NOMEM;
    }
  }
  rc = sqlite3_finalize(pStmt);
  if( rc ) return rc;

  zSql = sqlite3MPrintf(db, 
      "SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat3", zDb);
  if( !zSql ){
    return SQLITE_NOMEM;
  }
  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
  sqlite3DbFree(db, zSql);
  if( rc ) return rc;

  while( sqlite3_step(pStmt)==SQLITE_ROW ){
    char *zIndex;   /* Index name */
    Index *pIdx;    /* Pointer to the index object */
    int i;          /* Loop counter */
    tRowcnt sumEq;  /* Sum of the nEq values */

    zIndex = (char *)sqlite3_column_text(pStmt, 0);
    if( zIndex==0 ) continue;
    pIdx = sqlite3FindIndex(db, zIndex, zDb);
    if( pIdx==0 ) continue;
    if( pIdx==pPrevIdx ){
      idx++;
    }else{
      pPrevIdx = pIdx;
      idx = 0;
    }
    assert( idx<pIdx->nSample );
    pSample = &pIdx->aSample[idx];
    pSample->nEq = (tRowcnt)sqlite3_column_int64(pStmt, 1);
    pSample->nLt = (tRowcnt)sqlite3_column_int64(pStmt, 2);
    pSample->nDLt = (tRowcnt)sqlite3_column_int64(pStmt, 3);
    if( idx==pIdx->nSample-1 ){
      if( pSample->nDLt>0 ){
        for(i=0, sumEq=0; i<=idx-1; i++) sumEq += pIdx->aSample[i].nEq;
        pIdx->avgEq = (pSample->nLt - sumEq)/pSample->nDLt;
      }
      if( pIdx->avgEq<=0 ) pIdx->avgEq = 1;
    }
    eType = sqlite3_column_type(pStmt, 4);
    pSample->eType = (u8)eType;
    switch( eType ){
      case SQLITE_INTEGER: {
        pSample->u.i = sqlite3_column_int64(pStmt, 4);
        break;
      }
      case SQLITE_FLOAT: {
        pSample->u.r = sqlite3_column_double(pStmt, 4);
        break;
      }
      case SQLITE_NULL: {
        break;
      }
      default: assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB ); {
        const char *z = (const char *)(
              (eType==SQLITE_BLOB) ?
              sqlite3_column_blob(pStmt, 4):
              sqlite3_column_text(pStmt, 4)
           );
        int n = z ? sqlite3_column_bytes(pStmt, 4) : 0;
        pSample->nByte = n;
        if( n < 1){
          pSample->u.z = 0;
        }else{
          pSample->u.z = sqlite3Malloc(n);
          if( pSample->u.z==0 ){
            db->mallocFailed = 1;
            sqlite3_finalize(pStmt);
            return SQLITE_NOMEM;
          }
          memcpy(pSample->u.z, z, n);
        }
      }
    }
  }
  return sqlite3_finalize(pStmt);
}
#endif /* SQLITE_ENABLE_STAT3 */

/*
** Load the content of the sqlite_stat1 and sqlite_stat3 tables. The
** contents of sqlite_stat1 are used to populate the Index.aiRowEst[]
** arrays. The contents of sqlite_stat3 are used to populate the
** Index.aSample[] arrays.
**
** If the sqlite_stat1 table is not present in the database, SQLITE_ERROR
** is returned. In this case, even if SQLITE_ENABLE_STAT3 was defined 
** during compilation and the sqlite_stat3 table is present, no data is 
** read from it.
**
** If SQLITE_ENABLE_STAT3 was defined during compilation and the 
** sqlite_stat3 table is not present in the database, SQLITE_ERROR is
** returned. However, in this case, data is read from the sqlite_stat1
** table (if it is present) before returning.
**
** If an OOM error occurs, this function always sets db->mallocFailed.
** This means if the caller does not care about other errors, the return
** code may be ignored.
*/
................................................................................
  assert( db->aDb[iDb].pBt!=0 );

  /* Clear any prior statistics */
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    sqlite3DefaultRowEst(pIdx);
#ifdef SQLITE_ENABLE_STAT3
    sqlite3DeleteIndexSamples(db, pIdx);
    pIdx->aSample = 0;
#endif
  }

  /* Check to make sure the sqlite_stat1 table exists */
  sInfo.db = db;
  sInfo.zDatabase = db->aDb[iDb].zName;
  if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){
    return SQLITE_ERROR;
  }

  /* Load new statistics out of the sqlite_stat1 table */
  zSql = sqlite3MPrintf(db, 
      "SELECT tbl,idx,stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
  if( zSql==0 ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
    sqlite3DbFree(db, zSql);
  }


  /* Load the statistics from the sqlite_stat3 table. */
#ifdef SQLITE_ENABLE_STAT3



  if( rc==SQLITE_OK ){



    rc = loadStat3(db, sInfo.zDatabase);






























































  }
#endif

  if( rc==SQLITE_NOMEM ){
    db->mallocFailed = 1;
  }
  return rc;
................................................................................
      iDestroyed = iLargest;
    }
  }
#endif
}

/*
** Remove entries from the sqlite_statN tables (for N in (1,2,3))
** after a DROP INDEX or DROP TABLE command.
*/
static void sqlite3ClearStatTables(
  Parse *pParse,         /* The parsing context */
  int iDb,               /* The database number */
  const char *zType,     /* "idx" or "tbl" */
  const char *zName      /* Name of index or table */
){

  int i;
  const char *zDbName = pParse->db->aDb[iDb].zName;
  for(i=1; i<=3; i++){
    char zTab[24];
    sqlite3_snprintf(sizeof(zTab),zTab,"sqlite_stat%d",i);
    if( sqlite3FindTable(pParse->db, zTab, zDbName) ){
      sqlite3NestedParse(pParse,
        "DELETE FROM %Q.%s WHERE %s=%Q",

        zDbName, zTab, zType, zName
      );
    }
  }
}

/*
** Generate code to drop a table.
*/
SQLITE_PRIVATE void sqlite3CodeDropTable(Parse *pParse, Table *pTab, int iDb, int isView){
  Vdbe *v;
  sqlite3 *db = pParse->db;
  Trigger *pTrigger;
  Db *pDb = &db->aDb[iDb];

  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  sqlite3BeginWriteOperation(pParse, 1, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(pTab) ){
    sqlite3VdbeAddOp0(v, OP_VBegin);
  }
#endif

  /* Drop all triggers associated with the table being dropped. Code
  ** is generated to remove entries from sqlite_master and/or
  ** sqlite_temp_master if required.
  */
  pTrigger = sqlite3TriggerList(pParse, pTab);
  while( pTrigger ){
    assert( pTrigger->pSchema==pTab->pSchema || 
        pTrigger->pSchema==db->aDb[1].pSchema );
    sqlite3DropTriggerPtr(pParse, pTrigger);
    pTrigger = pTrigger->pNext;
  }

#ifndef SQLITE_OMIT_AUTOINCREMENT
  /* Remove any entries of the sqlite_sequence table associated with
  ** the table being dropped. This is done before the table is dropped
  ** at the btree level, in case the sqlite_sequence table needs to
  ** move as a result of the drop (can happen in auto-vacuum mode).
  */
  if( pTab->tabFlags & TF_Autoincrement ){
    sqlite3NestedParse(pParse,
      "DELETE FROM %Q.sqlite_sequence WHERE name=%Q",
      pDb->zName, pTab->zName
    );
  }
#endif

  /* Drop all SQLITE_MASTER table and index entries that refer to the
  ** table. The program name loops through the master table and deletes
  ** every row that refers to a table of the same name as the one being
  ** dropped. Triggers are handled seperately because a trigger can be
  ** created in the temp database that refers to a table in another
  ** database.
  */
  sqlite3NestedParse(pParse, 
      "DELETE FROM %Q.%s WHERE tbl_name=%Q and type!='trigger'",
      pDb->zName, SCHEMA_TABLE(iDb), pTab->zName);
  if( !isView && !IsVirtual(pTab) ){
    destroyTable(pParse, pTab);
  }

  /* Remove the table entry from SQLite's internal schema and modify
  ** the schema cookie.
  */
  if( IsVirtual(pTab) ){
    sqlite3VdbeAddOp4(v, OP_VDestroy, iDb, 0, 0, pTab->zName, 0);
  }
  sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);
  sqlite3ChangeCookie(pParse, iDb);
  sqliteViewResetAll(db, iDb);
}

/*
** This routine is called to do the work of a DROP TABLE statement.
** pName is the name of the table to be dropped.
*/
SQLITE_PRIVATE void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
  Table *pTab;
................................................................................
      goto exit_drop_table;
    }
    if( sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){
      goto exit_drop_table;
    }
  }
#endif
  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 
    && sqlite3StrNICmp(pTab->zName, "sqlite_stat", 11)!=0 ){
    sqlite3ErrorMsg(pParse, "table %s may not be dropped", pTab->zName);
    goto exit_drop_table;
  }

#ifndef SQLITE_OMIT_VIEW
  /* Ensure DROP TABLE is not used on a view, and DROP VIEW is not used
  ** on a table.
................................................................................
#endif

  /* Generate code to remove the table from the master table
  ** on disk.
  */
  v = sqlite3GetVdbe(pParse);
  if( v ){


    sqlite3BeginWriteOperation(pParse, 1, iDb);












































    sqlite3ClearStatTables(pParse, iDb, "tbl", pTab->zName);

    sqlite3FkDropTable(pParse, pName, pTab);
    sqlite3CodeDropTable(pParse, pTab, iDb, isView);
  }












exit_drop_table:
  sqlite3SrcListDelete(db, pName);
}

/*
** This routine is called to create a new foreign key on the table
................................................................................
** the index already exists and must be cleared before being refilled and
** the root page number of the index is taken from pIndex->tnum.
*/
static void sqlite3RefillIndex(Parse *pParse, Index *pIndex, int memRootPage){
  Table *pTab = pIndex->pTable;  /* The table that is indexed */
  int iTab = pParse->nTab++;     /* Btree cursor used for pTab */
  int iIdx = pParse->nTab++;     /* Btree cursor used for pIndex */
  int iSorter;                   /* Cursor opened by OpenSorter (if in use) */
  int addr1;                     /* Address of top of loop */
  int addr2;                     /* Address to jump to for next iteration */
  int tnum;                      /* Root page of index */
  Vdbe *v;                       /* Generate code into this virtual machine */
  KeyInfo *pKey;                 /* KeyInfo for index */
#ifdef SQLITE_OMIT_MERGE_SORT
  int regIdxKey;                 /* Registers containing the index key */
#endif
  int regRecord;                 /* Register holding assemblied index record */
  sqlite3 *db = pParse->db;      /* The database connection */
  int iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);

#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_REINDEX, pIndex->zName, 0,
      db->aDb[iDb].zName ) ){
................................................................................
    sqlite3VdbeChangeP5(v, 1);
  }

#ifndef SQLITE_OMIT_MERGE_SORT
  /* Open the sorter cursor if we are to use one. */
  iSorter = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_SorterOpen, iSorter, 0, 0, (char*)pKey, P4_KEYINFO);
#else
  iSorter = iTab;
#endif

  /* Open the table. Loop through all rows of the table, inserting index
  ** records into the sorter. */
  sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
  addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);

  regRecord = sqlite3GetTempReg(pParse);


#ifndef SQLITE_OMIT_MERGE_SORT
  sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);
  sqlite3VdbeAddOp2(v, OP_SorterInsert, iSorter, regRecord);
  sqlite3VdbeAddOp2(v, OP_Next, iTab, addr1+1);
  sqlite3VdbeJumpHere(v, addr1);
  addr1 = sqlite3VdbeAddOp2(v, OP_SorterSort, iSorter, 0);
  if( pIndex->onError!=OE_None ){
    int j2 = sqlite3VdbeCurrentAddr(v) + 3;
    sqlite3VdbeAddOp2(v, OP_Goto, 0, j2);
................................................................................
  }else{
    addr2 = sqlite3VdbeCurrentAddr(v);
  }
  sqlite3VdbeAddOp2(v, OP_SorterData, iSorter, regRecord);
  sqlite3VdbeAddOp3(v, OP_IdxInsert, iIdx, regRecord, 1);
  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
#else
  regIdxKey = sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);
  addr2 = addr1 + 1;
  if( pIndex->onError!=OE_None ){
    const int regRowid = regIdxKey + pIndex->nColumn;
    const int j2 = sqlite3VdbeCurrentAddr(v) + 2;
    void * const pRegKey = SQLITE_INT_TO_PTR(regIdxKey);

    /* The registers accessed by the OP_IsUnique opcode were allocated
    ** using sqlite3GetTempRange() inside of the sqlite3GenerateIndexKey()
................................................................................
    /* Use the two-part index name to determine the database 
    ** to search for the table. 'Fix' the table name to this db
    ** before looking up the table.
    */
    assert( pName1 && pName2 );
    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
    if( iDb<0 ) goto exit_create_index;
    assert( pName && pName->z );

#ifndef SQLITE_OMIT_TEMPDB
    /* If the index name was unqualified, check if the the table
    ** is a temp table. If so, set the database to 1. Do not do this
    ** if initialising a database schema.
    */
    if( !db->init.busy ){
................................................................................
    }
    pTab = sqlite3LocateTable(pParse, 0, pTblName->a[0].zName, 
        pTblName->a[0].zDatabase);
    if( !pTab || db->mallocFailed ) goto exit_create_index;
    assert( db->aDb[iDb].pSchema==pTab->pSchema );
  }else{
    assert( pName==0 );
    assert( pStart==0 );
    pTab = pParse->pNewTable;
    if( !pTab ) goto exit_create_index;
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  }
  pDb = &db->aDb[iDb];

  assert( pTab!=0 );
................................................................................
  ** If pName==0 it means that we are
  ** dealing with a primary key or UNIQUE constraint.  We have to invent our
  ** own name.
  */
  if( pName ){
    zName = sqlite3NameFromToken(db, pName);
    if( zName==0 ) goto exit_create_index;
    assert( pName->z!=0 );
    if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
      goto exit_create_index;
    }
    if( !db->init.busy ){
      if( sqlite3FindTable(db, zName, 0)!=0 ){
        sqlite3ErrorMsg(pParse, "there is already a table named %s", zName);
        goto exit_create_index;
................................................................................
  /* 
  ** Allocate the index structure. 
  */
  nName = sqlite3Strlen30(zName);
  nCol = pList->nExpr;
  pIndex = sqlite3DbMallocZero(db, 
      sizeof(Index) +              /* Index structure  */
      sizeof(tRowcnt)*(nCol+1) +   /* Index.aiRowEst   */
      sizeof(int)*nCol +           /* Index.aiColumn   */

      sizeof(char *)*nCol +        /* Index.azColl     */
      sizeof(u8)*nCol +            /* Index.aSortOrder */
      nName + 1 +                  /* Index.zName      */
      nExtra                       /* Collation sequence names */
  );
  if( db->mallocFailed ){
    goto exit_create_index;
  }
  pIndex->aiRowEst = (tRowcnt*)(&pIndex[1]);
  pIndex->azColl = (char**)(&pIndex->aiRowEst[nCol+1]);
  pIndex->aiColumn = (int *)(&pIndex->azColl[nCol]);

  pIndex->aSortOrder = (u8 *)(&pIndex->aiColumn[nCol]);
  pIndex->zName = (char *)(&pIndex->aSortOrder[nCol]);
  zExtra = (char *)(&pIndex->zName[nName+1]);
  memcpy(pIndex->zName, zName, nName+1);
  pIndex->pTable = pTab;
  pIndex->nColumn = pList->nExpr;
  pIndex->onError = (u8)onError;
  pIndex->autoIndex = (u8)(pName==0);
................................................................................
**           aiRowEst[N]>=1
**
** Apart from that, we have little to go on besides intuition as to
** how aiRowEst[] should be initialized.  The numbers generated here
** are based on typical values found in actual indices.
*/
SQLITE_PRIVATE void sqlite3DefaultRowEst(Index *pIdx){
  tRowcnt *a = pIdx->aiRowEst;
  int i;
  tRowcnt n;
  assert( a!=0 );
  a[0] = pIdx->pTable->nRowEst;
  if( a[0]<10 ) a[0] = 10;
  n = 10;
  for(i=1; i<=pIdx->nColumn; i++){
    a[i] = n;
    if( n>5 ) n--;
................................................................................
  sqlite3VdbeAddOp2(v, OP_AutoCommit, 0, 0);
}

/*
** Commit a transaction
*/
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse *pParse){

  Vdbe *v;

  assert( pParse!=0 );
  assert( pParse->db!=0 );


  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "COMMIT", 0, 0) ){
    return;
  }
  v = sqlite3GetVdbe(pParse);
  if( v ){
    sqlite3VdbeAddOp2(v, OP_AutoCommit, 1, 0);
  }
}

/*
** Rollback a transaction
*/
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse *pParse){

  Vdbe *v;

  assert( pParse!=0 );
  assert( pParse->db!=0 );


  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "ROLLBACK", 0, 0) ){
    return;
  }
  v = sqlite3GetVdbe(pParse);
  if( v ){
    sqlite3VdbeAddOp2(v, OP_AutoCommit, 1, 1);
  }
................................................................................
  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){

      for(i=0; i<n; i++){
        z1[i] = (char)sqlite3Toupper(z2[i]);
      }
      sqlite3_result_text(context, z1, n, sqlite3_free);
    }
  }
}
static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  char *z1;
  const char *z2;
  int i, n;
  UNUSED_PARAMETER(argc);
  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){

      for(i=0; i<n; i++){
        z1[i] = sqlite3Tolower(z2[i]);
      }
      sqlite3_result_text(context, z1, n, sqlite3_free);
    }
  }
}


#if 0  /* This function is never used. */
/*
................................................................................
    sqlite3ExprDelete(db, pWhen);
    sqlite3ExprListDelete(db, pList);
    sqlite3SelectDelete(db, pSelect);
    if( db->mallocFailed==1 ){
      fkTriggerDelete(db, pTrigger);
      return 0;
    }
    assert( pStep!=0 );

    switch( action ){
      case OE_Restrict:
        pStep->op = TK_SELECT; 
        break;
      case OE_Cascade: 
        if( !pChanges ){ 
................................................................................
  ** the extra complication to make this rule less restrictive is probably
  ** not worth the effort.  Ticket [6284df89debdfa61db8073e062908af0c9b6118e]
  */
  if( (pParse->db->flags & SQLITE_ForeignKeys)!=0 && pDest->pFKey!=0 ){
    return 0;
  }
#endif
  if( (pParse->db->flags & SQLITE_CountRows)!=0 ){
    return 0;
  }

  /* If we get this far, it means either:
  **
  **    *   We can always do the transfer if the table contains an
  **        an integer primary key
  **
  **    *   We can conditionally do the transfer if the destination
................................................................................
  int  (*bind_text)(sqlite3_stmt*,int,const char*,int n,void(*)(void*));
  int  (*bind_text16)(sqlite3_stmt*,int,const void*,int,void(*)(void*));
  int  (*bind_value)(sqlite3_stmt*,int,const sqlite3_value*);
  int  (*busy_handler)(sqlite3*,int(*)(void*,int),void*);
  int  (*busy_timeout)(sqlite3*,int ms);
  int  (*changes)(sqlite3*);
  int  (*close)(sqlite3*);
  int  (*collation_needed)(sqlite3*,void*,void(*)(void*,sqlite3*,
                           int eTextRep,const char*));
  int  (*collation_needed16)(sqlite3*,void*,void(*)(void*,sqlite3*,
                             int eTextRep,const void*));
  const void * (*column_blob)(sqlite3_stmt*,int iCol);
  int  (*column_bytes)(sqlite3_stmt*,int iCol);
  int  (*column_bytes16)(sqlite3_stmt*,int iCol);
  int  (*column_count)(sqlite3_stmt*pStmt);
  const char * (*column_database_name)(sqlite3_stmt*,int);
  const void * (*column_database_name16)(sqlite3_stmt*,int);
  const char * (*column_decltype)(sqlite3_stmt*,int i);
................................................................................
  const unsigned char * (*column_text)(sqlite3_stmt*,int iCol);
  const void * (*column_text16)(sqlite3_stmt*,int iCol);
  int  (*column_type)(sqlite3_stmt*,int iCol);
  sqlite3_value* (*column_value)(sqlite3_stmt*,int iCol);
  void * (*commit_hook)(sqlite3*,int(*)(void*),void*);
  int  (*complete)(const char*sql);
  int  (*complete16)(const void*sql);
  int  (*create_collation)(sqlite3*,const char*,int,void*,
                           int(*)(void*,int,const void*,int,const void*));
  int  (*create_collation16)(sqlite3*,const void*,int,void*,
                             int(*)(void*,int,const void*,int,const void*));
  int  (*create_function)(sqlite3*,const char*,int,int,void*,
                          void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
                          void (*xStep)(sqlite3_context*,int,sqlite3_value**),
                          void (*xFinal)(sqlite3_context*));
  int  (*create_function16)(sqlite3*,const void*,int,int,void*,
                            void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
                            void (*xStep)(sqlite3_context*,int,sqlite3_value**),
                            void (*xFinal)(sqlite3_context*));
  int (*create_module)(sqlite3*,const char*,const sqlite3_module*,void*);
  int  (*data_count)(sqlite3_stmt*pStmt);
  sqlite3 * (*db_handle)(sqlite3_stmt*);
  int (*declare_vtab)(sqlite3*,const char*);
  int  (*enable_shared_cache)(int);
  int  (*errcode)(sqlite3*db);
  const char * (*errmsg)(sqlite3*);
................................................................................
  void  (*result_null)(sqlite3_context*);
  void  (*result_text)(sqlite3_context*,const char*,int,void(*)(void*));
  void  (*result_text16)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_text16be)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_text16le)(sqlite3_context*,const void*,int,void(*)(void*));
  void  (*result_value)(sqlite3_context*,sqlite3_value*);
  void * (*rollback_hook)(sqlite3*,void(*)(void*),void*);
  int  (*set_authorizer)(sqlite3*,int(*)(void*,int,const char*,const char*,
                         const char*,const char*),void*);
  void  (*set_auxdata)(sqlite3_context*,int,void*,void (*)(void*));
  char * (*snprintf)(int,char*,const char*,...);
  int  (*step)(sqlite3_stmt*);
  int  (*table_column_metadata)(sqlite3*,const char*,const char*,const char*,
                                char const**,char const**,int*,int*,int*);
  void  (*thread_cleanup)(void);
  int  (*total_changes)(sqlite3*);
  void * (*trace)(sqlite3*,void(*xTrace)(void*,const char*),void*);
  int  (*transfer_bindings)(sqlite3_stmt*,sqlite3_stmt*);
  void * (*update_hook)(sqlite3*,void(*)(void*,int ,char const*,char const*,
                                         sqlite_int64),void*);
  void * (*user_data)(sqlite3_context*);
  const void * (*value_blob)(sqlite3_value*);
  int  (*value_bytes)(sqlite3_value*);
  int  (*value_bytes16)(sqlite3_value*);
  double  (*value_double)(sqlite3_value*);
  int  (*value_int)(sqlite3_value*);
  sqlite_int64  (*value_int64)(sqlite3_value*);
................................................................................
  /* Added ??? */
  int (*overload_function)(sqlite3*, const char *zFuncName, int nArg);
  /* Added by 3.3.13 */
  int (*prepare_v2)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
  int (*prepare16_v2)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
  int (*clear_bindings)(sqlite3_stmt*);
  /* Added by 3.4.1 */
  int (*create_module_v2)(sqlite3*,const char*,const sqlite3_module*,void*,
                          void (*xDestroy)(void *));
  /* Added by 3.5.0 */
  int (*bind_zeroblob)(sqlite3_stmt*,int,int);
  int (*blob_bytes)(sqlite3_blob*);
  int (*blob_close)(sqlite3_blob*);
  int (*blob_open)(sqlite3*,const char*,const char*,const char*,sqlite3_int64,
                   int,sqlite3_blob**);
  int (*blob_read)(sqlite3_blob*,void*,int,int);
  int (*blob_write)(sqlite3_blob*,const void*,int,int);
  int (*create_collation_v2)(sqlite3*,const char*,int,void*,
                             int(*)(void*,int,const void*,int,const void*),
                             void(*)(void*));
  int (*file_control)(sqlite3*,const char*,int,void*);
  sqlite3_int64 (*memory_highwater)(int);
  sqlite3_int64 (*memory_used)(void);
  sqlite3_mutex *(*mutex_alloc)(int);
  void (*mutex_enter)(sqlite3_mutex*);
  void (*mutex_free)(sqlite3_mutex*);
  void (*mutex_leave)(sqlite3_mutex*);
................................................................................
  int (*backup_finish)(sqlite3_backup*);
  sqlite3_backup *(*backup_init)(sqlite3*,const char*,sqlite3*,const char*);
  int (*backup_pagecount)(sqlite3_backup*);
  int (*backup_remaining)(sqlite3_backup*);
  int (*backup_step)(sqlite3_backup*,int);
  const char *(*compileoption_get)(int);
  int (*compileoption_used)(const char*);
  int (*create_function_v2)(sqlite3*,const char*,int,int,void*,
                            void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
                            void (*xStep)(sqlite3_context*,int,sqlite3_value**),
                            void (*xFinal)(sqlite3_context*),
                            void(*xDestroy)(void*));
  int (*db_config)(sqlite3*,int,...);
  sqlite3_mutex *(*db_mutex)(sqlite3*);
  int (*db_status)(sqlite3*,int,int*,int*,int);
  int (*extended_errcode)(sqlite3*);
  void (*log)(int,const char*,...);
  sqlite3_int64 (*soft_heap_limit64)(sqlite3_int64);
  const char *(*sourceid)(void);
................................................................................
  char **pzErrMsg       /* Put error message here if not 0 */
){
  sqlite3_vfs *pVfs = db->pVfs;
  void *handle;
  int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
  char *zErrmsg = 0;
  void **aHandle;
  int nMsg = 300 + sqlite3Strlen30(zFile);

  if( pzErrMsg ) *pzErrMsg = 0;

  /* Ticket #1863.  To avoid a creating security problems for older
  ** applications that relink against newer versions of SQLite, the
  ** ability to run load_extension is turned off by default.  One
  ** must call sqlite3_enable_load_extension() to turn on extension
................................................................................
    }
    return SQLITE_ERROR;
  }
  xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
                   sqlite3OsDlSym(pVfs, handle, zProc);
  if( xInit==0 ){
    if( pzErrMsg ){
      nMsg += sqlite3Strlen30(zProc);
      *pzErrMsg = zErrmsg = sqlite3_malloc(nMsg);
      if( zErrmsg ){
        sqlite3_snprintf(nMsg, zErrmsg,
            "no entry point [%s] in shared library [%s]", zProc,zFile);
        sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
      }
      sqlite3OsDlClose(pVfs, handle);
................................................................................
  if( sqlite3StrICmp(zLeft,"page_count")==0
   || sqlite3StrICmp(zLeft,"max_page_count")==0
  ){
    int iReg;
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
    sqlite3CodeVerifySchema(pParse, iDb);
    iReg = ++pParse->nMem;
    if( sqlite3Tolower(zLeft[0])=='p' ){
      sqlite3VdbeAddOp2(v, OP_Pagecount, iDb, iReg);
    }else{
      sqlite3VdbeAddOp3(v, OP_MaxPgcnt, iDb, iReg, sqlite3Atoi(zRight));
    }
    sqlite3VdbeAddOp2(v, OP_ResultRow, iReg, 1);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLeft, SQLITE_TRANSIENT);
................................................................................
  **  PRAGMA [database.]journal_mode =
  **                      (delete|persist|off|truncate|memory|wal|off)
  */
  if( sqlite3StrICmp(zLeft,"journal_mode")==0 ){
    int eMode;        /* One of the PAGER_JOURNALMODE_XXX symbols */
    int ii;           /* Loop counter */

    /* Force the schema to be loaded on all databases.  This causes all
    ** database files to be opened and the journal_modes set.  This is
    ** necessary because subsequent processing must know if the databases
    ** are in WAL mode. */
    if( sqlite3ReadSchema(pParse) ){
      goto pragma_out;
    }

    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "journal_mode", SQLITE_STATIC);

................................................................................
    static const VdbeOpList endCode[] = {
      { OP_AddImm,      1, 0,        0},    /* 0 */
      { OP_IfNeg,       1, 0,        0},    /* 1 */
      { OP_String8,     0, 3,        0},    /* 2 */
      { OP_ResultRow,   3, 1,        0},
    };

    int isQuick = (sqlite3Tolower(zLeft[0])=='q');

    /* Initialize the VDBE program */
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
    pParse->nMem = 6;
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "integrity_check", SQLITE_STATIC);

................................................................................
){
  Select *pNew;
  Select standin;
  sqlite3 *db = pParse->db;
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
  assert( db->mallocFailed || !pOffset || pLimit ); /* OFFSET implies LIMIT */
  if( pNew==0 ){
    assert( db->mallocFailed );
    pNew = &standin;
    memset(pNew, 0, sizeof(*pNew));
  }
  if( pEList==0 ){
    pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0));
  }
  pNew->pEList = pEList;
................................................................................
  if( db->mallocFailed ) {
    clearSelect(db, pNew);
    if( pNew!=&standin ) sqlite3DbFree(db, pNew);
    pNew = 0;
  }else{
    assert( pNew->pSrc!=0 || pParse->nErr>0 );
  }
  assert( pNew!=&standin );
  return pNew;
}

/*
** Delete the given Select structure and all of its substructures.
*/
SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3 *db, Select *p){
................................................................................
               || p->pRight->u.zToken==0 || p->pRight->u.zToken[0]!=0 );
    if( (zName = pEList->a[i].zName)!=0 ){
      /* If the column contains an "AS <name>" phrase, use <name> as the name */
      zName = sqlite3DbStrDup(db, zName);
    }else{
      Expr *pColExpr = p;  /* The expression that is the result column name */
      Table *pTab;         /* Table associated with this expression */
      while( pColExpr->op==TK_DOT ){
        pColExpr = pColExpr->pRight;
        assert( pColExpr!=0 );
      }
      if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){
        /* For columns use the column name name */
        int iCol = pColExpr->iColumn;
        pTab = pColExpr->pTab;
        if( iCol<0 ) iCol = pTab->iPKey;
        zName = sqlite3MPrintf(db, "%s",
                 iCol>=0 ? pTab->aCol[iCol].zName : "rowid");
................................................................................
        if( pIdx->onError==OE_Replace ){
          openAll = 1;
          break;
        }
      }
    }
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      assert( aRegIdx );
      if( openAll || aRegIdx[i]>0 ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
                       (char*)pKey, P4_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }
................................................................................
  ** all record selected by the WHERE clause have been updated.
  */
  sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
  sqlite3VdbeJumpHere(v, addr);

  /* Close all tables */
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    assert( aRegIdx );
    if( openAll || aRegIdx[i]>0 ){
      sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0);
    }
  }
  sqlite3VdbeAddOp2(v, OP_Close, iCur, 0);

  /* Update the sqlite_sequence table by storing the content of the
................................................................................
    return SQLITE_NOMEM;
  }
  if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
    return sqlite3_errcode(db);
  }
  VVA_ONLY( rc = ) sqlite3_step(pStmt);
  assert( rc!=SQLITE_ROW || (db->flags&SQLITE_CountRows) );
  return vacuumFinalize(db, pStmt, pzErrMsg);
}

/*
** Execute zSql on database db. The statement returns exactly
** one column. Execute this as SQL on the same database.
*/
................................................................................
      "  SELECT type, name, tbl_name, rootpage, sql"
      "    FROM main.sqlite_master"
      "   WHERE type='view' OR type='trigger'"
      "      OR (type='table' AND rootpage=0)"
  );
  if( rc ) goto end_of_vacuum;

  /* At this point, there is a write transaction open on both the 
  ** vacuum database and the main database. Assuming no error occurs,
  ** both transactions are closed by this block - the main database
  ** transaction by sqlite3BtreeCopyFile() and the other by an explicit
  ** call to sqlite3BtreeCommit().



  */
  {
    u32 meta;
    int i;

    /* This array determines which meta meta values are preserved in the
    ** vacuum.  Even entries are the meta value number and odd entries
................................................................................
  assert( op==SAVEPOINT_RELEASE||op==SAVEPOINT_ROLLBACK||op==SAVEPOINT_BEGIN );
  assert( iSavepoint>=0 );
  if( db->aVTrans ){
    int i;
    for(i=0; rc==SQLITE_OK && i<db->nVTrans; i++){
      VTable *pVTab = db->aVTrans[i];
      const sqlite3_module *pMod = pVTab->pMod->pModule;
      if( pVTab->pVtab && pMod->iVersion>=2 ){
        int (*xMethod)(sqlite3_vtab *, int);
        switch( op ){
          case SAVEPOINT_BEGIN:
            xMethod = pMod->xSavepoint;
            pVTab->iSavepoint = iSavepoint+1;
            break;
          case SAVEPOINT_ROLLBACK:
................................................................................
            xMethod = pMod->xRollbackTo;
            break;
          default:
            xMethod = pMod->xRelease;
            break;
        }
        if( xMethod && pVTab->iSavepoint>iSavepoint ){
          rc = xMethod(pVTab->pVtab, iSavepoint);
        }
      }
    }
  }
  return rc;
}

................................................................................
#define TERM_DYNAMIC    0x01   /* Need to call sqlite3ExprDelete(db, pExpr) */
#define TERM_VIRTUAL    0x02   /* Added by the optimizer.  Do not code */
#define TERM_CODED      0x04   /* This term is already coded */
#define TERM_COPIED     0x08   /* Has a child */
#define TERM_ORINFO     0x10   /* Need to free the WhereTerm.u.pOrInfo object */
#define TERM_ANDINFO    0x20   /* Need to free the WhereTerm.u.pAndInfo obj */
#define TERM_OR_OK      0x40   /* Used during OR-clause processing */
#ifdef SQLITE_ENABLE_STAT3
#  define TERM_VNULL    0x80   /* Manufactured x>NULL or x<=NULL term */
#else
#  define TERM_VNULL    0x00   /* Disabled if not using stat3 */
#endif

/*
** An instance of the following structure holds all information about a
** WHERE clause.  Mostly this is a container for one or more WhereTerms.
**
** Explanation of pOuter:  For a WHERE clause of the form
**
**           a AND ((b AND c) OR (d AND e)) AND f
**
** There are separate WhereClause objects for the whole clause and for
** the subclauses "(b AND c)" and "(d AND e)".  The pOuter field of the
** subclauses points to the WhereClause object for the whole clause.
*/
struct WhereClause {
  Parse *pParse;           /* The parser context */
  WhereMaskSet *pMaskSet;  /* Mapping of table cursor numbers to bitmasks */
  Bitmask vmask;           /* Bitmask identifying virtual table cursors */
  WhereClause *pOuter;     /* Outer conjunction */
  u8 op;                   /* Split operator.  TK_AND or TK_OR */
  u16 wctrlFlags;          /* Might include WHERE_AND_ONLY */
  int nTerm;               /* Number of terms */
  int nSlot;               /* Number of entries in a[] */
  WhereTerm *a;            /* Each a[] describes a term of the WHERE cluase */
#if defined(SQLITE_SMALL_STACK)
  WhereTerm aStatic[1];    /* Initial static space for a[] */
#else
  WhereTerm aStatic[8];    /* Initial static space for a[] */
................................................................................

/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */
  WhereMaskSet *pMaskSet,  /* Mapping from table cursor numbers to bitmasks */
  u16 wctrlFlags           /* Might include WHERE_AND_ONLY */
){
  pWC->pParse = pParse;
  pWC->pMaskSet = pMaskSet;
  pWC->pOuter = 0;
  pWC->nTerm = 0;
  pWC->nSlot = ArraySize(pWC->aStatic);
  pWC->a = pWC->aStatic;
  pWC->vmask = 0;
  pWC->wctrlFlags = wctrlFlags;
}

/* Forward reference */
static void whereClauseClear(WhereClause*);

/*
** Deallocate all memory associated with a WhereOrInfo object.
................................................................................
  u32 op,               /* Mask of WO_xx values describing operator */
  Index *pIdx           /* Must be compatible with this index, if not NULL */
){
  WhereTerm *pTerm;
  int k;
  assert( iCur>=0 );
  op &= WO_ALL;
  for(; pWC; pWC=pWC->pOuter){
    for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
      if( pTerm->leftCursor==iCur
         && (pTerm->prereqRight & notReady)==0
         && pTerm->u.leftColumn==iColumn
         && (pTerm->eOperator & op)!=0
      ){
        if( pIdx && pTerm->eOperator!=WO_ISNULL ){
          Expr *pX = pTerm->pExpr;
          CollSeq *pColl;
          char idxaff;
          int j;
          Parse *pParse = pWC->pParse;
  
          idxaff = pIdx->pTable->aCol[iColumn].affinity;
          if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
  
          /* Figure out the collation sequence required from an index for
          ** it to be useful for optimising expression pX. Store this
          ** value in variable pColl.
          */
          assert(pX->pLeft);
          pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
          assert(pColl || pParse->nErr);
  
          for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
            if( NEVER(j>=pIdx->nColumn) ) return 0;
          }
          if( pColl && sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
        }
        return pTerm;
      }
    }
  }
  return 0;
}

/* Forward reference */
static void exprAnalyze(SrcList*, WhereClause*, int);
................................................................................
  if( op==TK_VARIABLE ){
    Vdbe *pReprepare = pParse->pReprepare;
    int iCol = pRight->iColumn;
    pVal = sqlite3VdbeGetValue(pReprepare, iCol, SQLITE_AFF_NONE);
    if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
      z = (char *)sqlite3_value_text(pVal);
    }
    sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
    assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
  }else if( op==TK_STRING ){
    z = pRight->u.zToken;
  }
  if( z ){
    cnt = 0;
    while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
................................................................................
      Expr *pPrefix;
      *pisComplete = c==wc[0] && z[cnt+1]==0;
      pPrefix = sqlite3Expr(db, TK_STRING, z);
      if( pPrefix ) pPrefix->u.zToken[cnt] = 0;
      *ppPrefix = pPrefix;
      if( op==TK_VARIABLE ){
        Vdbe *v = pParse->pVdbe;
        sqlite3VdbeSetVarmask(v, pRight->iColumn);
        if( *pisComplete && pRight->u.zToken[1] ){
          /* If the rhs of the LIKE expression is a variable, and the current
          ** value of the variable means there is no need to invoke the LIKE
          ** function, then no OP_Variable will be added to the program.
          ** This causes problems for the sqlite3_bind_parameter_name()
          ** API. To workaround them, add a dummy OP_Variable here.
          */ 
................................................................................
  */
  assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
  assert( pExpr->op==TK_OR );
  pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
  if( pOrInfo==0 ) return;
  pTerm->wtFlags |= TERM_ORINFO;
  pOrWc = &pOrInfo->wc;
  whereClauseInit(pOrWc, pWC->pParse, pMaskSet, pWC->wctrlFlags);
  whereSplit(pOrWc, pExpr, TK_OR);
  exprAnalyzeAll(pSrc, pOrWc);
  if( db->mallocFailed ) return;
  assert( pOrWc->nTerm>=2 );

  /*
  ** Compute the set of tables that might satisfy cases 1 or 2.
................................................................................
        WhereTerm *pAndTerm;
        int j;
        Bitmask b = 0;
        pOrTerm->u.pAndInfo = pAndInfo;
        pOrTerm->wtFlags |= TERM_ANDINFO;
        pOrTerm->eOperator = WO_AND;
        pAndWC = &pAndInfo->wc;
        whereClauseInit(pAndWC, pWC->pParse, pMaskSet, pWC->wctrlFlags);
        whereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
        exprAnalyzeAll(pSrc, pAndWC);
        pAndWC->pOuter = pWC;
        testcase( db->mallocFailed );
        if( !db->mallocFailed ){
          for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
            assert( pAndTerm->pExpr );
            if( allowedOp(pAndTerm->pExpr->op) ){
              b |= getMask(pMaskSet, pAndTerm->leftCursor);
            }
................................................................................
      pTerm->nChild = 1;
      pTerm->wtFlags |= TERM_COPIED;
      pNewTerm->prereqAll = pTerm->prereqAll;
    }
  }
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifdef SQLITE_ENABLE_STAT3
  /* When sqlite_stat3 histogram data is available an operator of the
  ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
  ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
  ** virtual term of that form.
  **
  ** Note that the virtual term must be tagged with TERM_VNULL.  This
  ** TERM_VNULL tag will suppress the not-null check at the beginning
  ** of the loop.  Without the TERM_VNULL flag, the not-null check at
................................................................................
      pNewTerm->iParent = idxTerm;
      pTerm = &pWC->a[idxTerm];
      pTerm->nChild = 1;
      pTerm->wtFlags |= TERM_COPIED;
      pNewTerm->prereqAll = pTerm->prereqAll;
    }
  }
#endif /* SQLITE_ENABLE_STAT */

  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}

................................................................................
){
#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  const int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur);  /* Bitmask for pSrc */
  WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm];        /* End of pWC->a[] */
  WhereTerm *pTerm;                 /* A single term of the WHERE clause */

  /* The OR-clause optimization is disallowed if the INDEXED BY or
  ** NOT INDEXED clauses are used or if the WHERE_AND_ONLY bit is set. */
  if( pSrc->notIndexed || pSrc->pIndex!=0 ){
    return;
  }
  if( pWC->wctrlFlags & WHERE_AND_ONLY ){
    return;
  }

  /* Search the WHERE clause terms for a usable WO_OR term. */
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( pTerm->eOperator==WO_OR 
     && ((pTerm->prereqAll & ~maskSrc) & notReady)==0
     && (pTerm->u.pOrInfo->indexable & maskSrc)!=0 
................................................................................
        if( pOrTerm->eOperator==WO_AND ){
          WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc;
          bestIndex(pParse, pAndWC, pSrc, notReady, notValid, 0, &sTermCost);
        }else if( pOrTerm->leftCursor==iCur ){
          WhereClause tempWC;
          tempWC.pParse = pWC->pParse;
          tempWC.pMaskSet = pWC->pMaskSet;
          tempWC.pOuter = pWC;
          tempWC.op = TK_AND;
          tempWC.a = pOrTerm;
          tempWC.wctrlFlags = 0;
          tempWC.nTerm = 1;
          bestIndex(pParse, &tempWC, pSrc, notReady, notValid, 0, &sTermCost);
        }else{
          continue;
        }
        rTotal += sTermCost.rCost;
        nRow += sTermCost.plan.nRow;
................................................................................
  /* Try to find a more efficient access pattern by using multiple indexes
  ** to optimize an OR expression within the WHERE clause. 
  */
  bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost);
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifdef SQLITE_ENABLE_STAT3
/*

** Estimate the location of a particular key among all keys in an
** index.  Store the results in aStat as follows:





**





**    aStat[0]      Est. number of rows less than pVal
**    aStat[1]      Est. number of rows equal to pVal
**





** Return SQLITE_OK on success.
*/

static int whereKeyStats(
  Parse *pParse,              /* Database connection */
  Index *pIdx,                /* Index to consider domain of */
  sqlite3_value *pVal,        /* Value to consider */
  int roundUp,                /* Round up if true.  Round down if false */
  tRowcnt *aStat              /* OUT: stats written here */
){
  tRowcnt n;
  IndexSample *aSample;
  int i, eType;
  int isEq = 0;
  i64 v;
  double r, rS;

  assert( roundUp==0 || roundUp==1 );

  assert( pIdx->nSample>0 );
  if( pVal==0 ) return SQLITE_ERROR;
  n = pIdx->aiRowEst[0];
  aSample = pIdx->aSample;

  eType = sqlite3_value_type(pVal);

  if( eType==SQLITE_INTEGER ){
    v = sqlite3_value_int64(pVal);
    r = (i64)v;
    for(i=0; i<pIdx->nSample; i++){
      if( aSample[i].eType==SQLITE_NULL ) continue;
      if( aSample[i].eType>=SQLITE_TEXT ) break;
      if( aSample[i].eType==SQLITE_INTEGER ){
        if( aSample[i].u.i>=v ){
          isEq = aSample[i].u.i==v;
          break;
        }
      }else{
        assert( aSample[i].eType==SQLITE_FLOAT );
        if( aSample[i].u.r>=r ){
          isEq = aSample[i].u.r==r;
          break;
        }
      }
    }
  }else if( eType==SQLITE_FLOAT ){
    r = sqlite3_value_double(pVal);

    for(i=0; i<pIdx->nSample; i++){
      if( aSample[i].eType==SQLITE_NULL ) continue;
      if( aSample[i].eType>=SQLITE_TEXT ) break;

      if( aSample[i].eType==SQLITE_FLOAT ){
        rS = aSample[i].u.r;
      }else{
        rS = aSample[i].u.i;
      }
      if( rS>=r ){
        isEq = rS==r;
        break;
      }
    }
  }else if( eType==SQLITE_NULL ){
    i = 0;

    if( aSample[0].eType==SQLITE_NULL ) isEq = 1;

  }else{
    assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
    for(i=0; i<pIdx->nSample; i++){
      if( aSample[i].eType==SQLITE_TEXT || aSample[i].eType==SQLITE_BLOB ){
        break;
      }
    }
    if( i<pIdx->nSample ){      
      sqlite3 *db = pParse->db;
      CollSeq *pColl;
      const u8 *z;





      if( eType==SQLITE_BLOB ){
        z = (const u8 *)sqlite3_value_blob(pVal);
        pColl = db->pDfltColl;
        assert( pColl->enc==SQLITE_UTF8 );
      }else{
        pColl = sqlite3GetCollSeq(db, SQLITE_UTF8, 0, *pIdx->azColl);
        if( pColl==0 ){
................................................................................
        z = (const u8 *)sqlite3ValueText(pVal, pColl->enc);
        if( !z ){
          return SQLITE_NOMEM;
        }
        assert( z && pColl && pColl->xCmp );
      }
      n = sqlite3ValueBytes(pVal, pColl->enc);
  
      for(; i<pIdx->nSample; i++){
        int c;
        int eSampletype = aSample[i].eType;
        if( eSampletype<eType ) continue;
        if( eSampletype!=eType ) break;
#ifndef SQLITE_OMIT_UTF16
        if( pColl->enc!=SQLITE_UTF8 ){
          int nSample;
          char *zSample = sqlite3Utf8to16(
              db, pColl->enc, aSample[i].u.z, aSample[i].nByte, &nSample
          );
          if( !zSample ){
................................................................................
          c = pColl->xCmp(pColl->pUser, nSample, zSample, n, z);
          sqlite3DbFree(db, zSample);
        }else
#endif
        {
          c = pColl->xCmp(pColl->pUser, aSample[i].nByte, aSample[i].u.z, n, z);
        }
        if( c>=0 ){
          if( c==0 ) isEq = 1;
          break;
        }
      }
    }


  }

  /* At this point, aSample[i] is the first sample that is greater than
  ** or equal to pVal.  Or if i==pIdx->nSample, then all samples are less
  ** than pVal.  If aSample[i]==pVal, then isEq==1.
  */
  if( isEq ){
    assert( i<pIdx->nSample );
    aStat[0] = aSample[i].nLt;
    aStat[1] = aSample[i].nEq;
  }else{
    tRowcnt iLower, iUpper, iGap;
    if( i==0 ){
      iLower = 0;
      iUpper = aSample[0].nLt;
    }else{
      iUpper = i>=pIdx->nSample ? n : aSample[i].nLt;
      iLower = aSample[i-1].nEq + aSample[i-1].nLt;
    }
    aStat[1] = pIdx->avgEq;
    if( iLower>=iUpper ){
      iGap = 0;
    }else{
      iGap = iUpper - iLower;
    }
    if( roundUp ){
      iGap = (iGap*2)/3;
    }else{
      iGap = iGap/3;
    }
    aStat[0] = iLower + iGap;
  }
  return SQLITE_OK;
}
#endif /* SQLITE_ENABLE_STAT3 */

/*
** If expression pExpr represents a literal value, set *pp to point to
** an sqlite3_value structure containing the same value, with affinity
** aff applied to it, before returning. It is the responsibility of the 
** caller to eventually release this structure by passing it to 
** sqlite3ValueFree().
................................................................................
** create an sqlite3_value structure containing this value, again with
** affinity aff applied to it, instead.
**
** If neither of the above apply, set *pp to NULL.
**
** If an error occurs, return an error code. Otherwise, SQLITE_OK.
*/
#ifdef SQLITE_ENABLE_STAT3
static int valueFromExpr(
  Parse *pParse, 
  Expr *pExpr, 
  u8 aff, 
  sqlite3_value **pp
){
  if( pExpr->op==TK_VARIABLE
   || (pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE)
  ){
    int iVar = pExpr->iColumn;
    sqlite3VdbeSetVarmask(pParse->pVdbe, iVar);
    *pp = sqlite3VdbeGetValue(pParse->pReprepare, iVar, aff);
    return SQLITE_OK;
  }
  return sqlite3ValueFromExpr(pParse->db, pExpr, SQLITE_UTF8, aff, pp);
}
#endif

................................................................................
** then nEq should be passed the value 1 (as the range restricted column,
** b, is the second left-most column of the index). Or, if the query is:
**
**   ... FROM t1 WHERE a > ? AND a < ? ...
**
** then nEq should be passed 0.
**
** The returned value is an integer divisor to reduce the estimated
** search space.  A return value of 1 means that range constraints are
** no help at all.  A return value of 2 means range constraints are
** expected to reduce the search space by half.  And so forth...


**
** In the absence of sqlite_stat3 ANALYZE data, each range inequality
** reduces the search space by a factor of 4.  Hence a single constraint (x>?)
** results in a return of 4 and a range constraint (x>? AND x<?) results
** in a return of 16.
*/
static int whereRangeScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index containing the range-compared column; "x" */
  int nEq,             /* index into p->aCol[] of the range-compared column */
  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
  double *pRangeDiv   /* OUT: Reduce search space by this divisor */
){
  int rc = SQLITE_OK;

#ifdef SQLITE_ENABLE_STAT3

  if( nEq==0 && p->nSample ){
    sqlite3_value *pRangeVal;


    tRowcnt iLower = 0;
    tRowcnt iUpper = p->aiRowEst[0];


    tRowcnt a[2];
    u8 aff = p->pTable->aCol[p->aiColumn[0]].affinity;

    if( pLower ){
      Expr *pExpr = pLower->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pRangeVal);
      assert( pLower->eOperator==WO_GT || pLower->eOperator==WO_GE );
      if( rc==SQLITE_OK
       && whereKeyStats(pParse, p, pRangeVal, 0, a)==SQLITE_OK
      ){
        iLower = a[0];
        if( pLower->eOperator==WO_GT ) iLower += a[1];
      }
      sqlite3ValueFree(pRangeVal);
    }
    if( rc==SQLITE_OK && pUpper ){
      Expr *pExpr = pUpper->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pRangeVal);
      assert( pUpper->eOperator==WO_LT || pUpper->eOperator==WO_LE );
      if( rc==SQLITE_OK
       && whereKeyStats(pParse, p, pRangeVal, 1, a)==SQLITE_OK
      ){
        iUpper = a[0];
        if( pUpper->eOperator==WO_LE ) iUpper += a[1];
      }
      sqlite3ValueFree(pRangeVal);
    }





    if( rc==SQLITE_OK ){
      if( iUpper<=iLower ){
        *pRangeDiv = (double)p->aiRowEst[0];


      }else{



        *pRangeDiv = (double)p->aiRowEst[0]/(double)(iUpper - iLower);
      }

      WHERETRACE(("range scan regions: %u..%u  div=%g\n",
                  (u32)iLower, (u32)iUpper, *pRangeDiv));
      return SQLITE_OK;
    }







  }





#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(p);
  UNUSED_PARAMETER(nEq);
#endif
  assert( pLower || pUpper );

  *pRangeDiv = (double)1;
  if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ) *pRangeDiv *= (double)4;
  if( pUpper ) *pRangeDiv *= (double)4;
  return rc;
}

#ifdef SQLITE_ENABLE_STAT3
/*
** Estimate the number of rows that will be returned based on
** an equality constraint x=VALUE and where that VALUE occurs in
** the histogram data.  This only works when x is the left-most
** column of an index and sqlite_stat3 histogram data is available
** for that index.  When pExpr==NULL that means the constraint is
** "x IS NULL" instead of "x=VALUE".
**
** Write the estimated row count into *pnRow and return SQLITE_OK. 
** If unable to make an estimate, leave *pnRow unchanged and return
** non-zero.
**
................................................................................
static int whereEqualScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index whose left-most column is pTerm */
  Expr *pExpr,         /* Expression for VALUE in the x=VALUE constraint */
  double *pnRow        /* Write the revised row estimate here */
){
  sqlite3_value *pRhs = 0;  /* VALUE on right-hand side of pTerm */

  u8 aff;                   /* Column affinity */
  int rc;                   /* Subfunction return code */

  tRowcnt a[2];             /* Statistics */

  assert( p->aSample!=0 );
  assert( p->nSample>0 );
  aff = p->pTable->aCol[p->aiColumn[0]].affinity;
  if( pExpr ){
    rc = valueFromExpr(pParse, pExpr, aff, &pRhs);
    if( rc ) goto whereEqualScanEst_cancel;
  }else{
    pRhs = sqlite3ValueNew(pParse->db);
  }
  if( pRhs==0 ) return SQLITE_NOTFOUND;
  rc = whereKeyStats(pParse, p, pRhs, 0, a);
  if( rc==SQLITE_OK ){


    WHERETRACE(("equality scan regions: %d\n", (int)a[1]));





    *pnRow = a[1];
  }

whereEqualScanEst_cancel:
  sqlite3ValueFree(pRhs);
  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT3) */

#ifdef SQLITE_ENABLE_STAT3
/*
** Estimate the number of rows that will be returned based on
** an IN constraint where the right-hand side of the IN operator
** is a list of values.  Example:
**
**        WHERE x IN (1,2,3,4)
**
................................................................................
*/
static int whereInScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index whose left-most column is pTerm */
  ExprList *pList,     /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
  double *pnRow        /* Write the revised row estimate here */
){



  int rc = SQLITE_OK;         /* Subfunction return code */
  double nEst;                /* Number of rows for a single term */
  double nRowEst = (double)0; /* New estimate of the number of rows */



  int i;                      /* Loop counter */



  assert( p->aSample!=0 );



  for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){






    nEst = p->aiRowEst[0];
    rc = whereEqualScanEst(pParse, p, pList->a[i].pExpr, &nEst);
    nRowEst += nEst;
  }











  if( rc==SQLITE_OK ){









    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];
    *pnRow = nRowEst;
    WHERETRACE(("IN row estimate: est=%g\n", nRowEst));

  }

  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT3) */


/*
** Find the best query plan for accessing a particular table.  Write the
** best query plan and its cost into the WhereCost object supplied as the
** last parameter.
**
................................................................................
){
  int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  Index *pProbe;              /* An index we are evaluating */
  Index *pIdx;                /* Copy of pProbe, or zero for IPK index */
  int eqTermMask;             /* Current mask of valid equality operators */
  int idxEqTermMask;          /* Index mask of valid equality operators */
  Index sPk;                  /* A fake index object for the primary key */
  tRowcnt aiRowEstPk[2];      /* The aiRowEst[] value for the sPk index */
  int aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
  int wsFlagMask;             /* Allowed flags in pCost->plan.wsFlag */

  /* Initialize the cost to a worst-case value */
  memset(pCost, 0, sizeof(*pCost));
  pCost->rCost = SQLITE_BIG_DBL;

................................................................................
    eqTermMask = WO_EQ|WO_IN;
    pIdx = 0;
  }

  /* Loop over all indices looking for the best one to use
  */
  for(; pProbe; pIdx=pProbe=pProbe->pNext){
    const tRowcnt * const aiRowEst = pProbe->aiRowEst;
    double cost;                /* Cost of using pProbe */
    double nRow;                /* Estimated number of rows in result set */
    double log10N = (double)1;  /* base-10 logarithm of nRow (inexact) */
    int rev;                    /* True to scan in reverse order */
    int wsFlags = 0;
    Bitmask used = 0;

    /* The following variables are populated based on the properties of
    ** index being evaluated. They are then used to determine the expected
    ** cost and number of rows returned.
................................................................................
    **
    **  bInEst:  
    **    Set to true if there was at least one "x IN (SELECT ...)" term used 
    **    in determining the value of nInMul.  Note that the RHS of the
    **    IN operator must be a SELECT, not a value list, for this variable
    **    to be true.
    **
    **  rangeDiv:
    **    An estimate of a divisor by which to reduce the search space due
    **    to inequality constraints.  In the absence of sqlite_stat3 ANALYZE


    **    data, a single inequality reduces the search space to 1/4rd its


    **    original size (rangeDiv==4).  Two inequalities reduce the search
    **    space to 1/16th of its original size (rangeDiv==16).
    **
    **  bSort:   
    **    Boolean. True if there is an ORDER BY clause that will require an 
    **    external sort (i.e. scanning the index being evaluated will not 
    **    correctly order records).
    **
    **  bLookup: 
................................................................................
    **
    **             SELECT a, b    FROM tbl WHERE a = 1;
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;                      /* Number of == or IN terms matching index */
    int bInEst = 0;               /* True if "x IN (SELECT...)" seen */
    int nInMul = 1;               /* Number of distinct equalities to lookup */
    double rangeDiv = (double)1;  /* Estimated reduction in search space */
    int nBound = 0;               /* Number of range constraints seen */
    int bSort = !!pOrderBy;       /* True if external sort required */
    int bDist = !!pDistinct;      /* True if index cannot help with DISTINCT */
    int bLookup = 0;              /* True if not a covering index */
    WhereTerm *pTerm;             /* A single term of the WHERE clause */
#ifdef SQLITE_ENABLE_STAT3
    WhereTerm *pFirstTerm = 0;    /* First term matching the index */
#endif

    /* Determine the values of nEq and nInMul */
    for(nEq=0; nEq<pProbe->nColumn; nEq++){
      int j = pProbe->aiColumn[nEq];
      pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pIdx);
      if( pTerm==0 ) break;
      wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
      testcase( pTerm->pWC!=pWC );
      if( pTerm->eOperator & WO_IN ){
        Expr *pExpr = pTerm->pExpr;
        wsFlags |= WHERE_COLUMN_IN;
        if( ExprHasProperty(pExpr, EP_xIsSelect) ){
          /* "x IN (SELECT ...)":  Assume the SELECT returns 25 rows */
          nInMul *= 25;
          bInEst = 1;
................................................................................
        }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
          /* "x IN (value, value, ...)" */
          nInMul *= pExpr->x.pList->nExpr;
        }
      }else if( pTerm->eOperator & WO_ISNULL ){
        wsFlags |= WHERE_COLUMN_NULL;
      }
#ifdef SQLITE_ENABLE_STAT3
      if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
      used |= pTerm->prereqRight;
    }

    /* Determine the value of rangeDiv */
    if( nEq<pProbe->nColumn && pProbe->bUnordered==0 ){
      int j = pProbe->aiColumn[nEq];
      if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
        WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx);
        WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx);
        whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &rangeDiv);
        if( pTop ){
          nBound = 1;
          wsFlags |= WHERE_TOP_LIMIT;
          used |= pTop->prereqRight;
          testcase( pTop->pWC!=pWC );
        }
        if( pBtm ){
          nBound++;
          wsFlags |= WHERE_BTM_LIMIT;
          used |= pBtm->prereqRight;
          testcase( pBtm->pWC!=pWC );
        }
        wsFlags |= (WHERE_COLUMN_RANGE|WHERE_ROWID_RANGE);
      }
    }else if( pProbe->onError!=OE_None ){
      testcase( wsFlags & WHERE_COLUMN_IN );
      testcase( wsFlags & WHERE_COLUMN_NULL );
      if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
................................................................................
    */
    nRow = (double)(aiRowEst[nEq] * nInMul);
    if( bInEst && nRow*2>aiRowEst[0] ){
      nRow = aiRowEst[0]/2;
      nInMul = (int)(nRow / aiRowEst[nEq]);
    }

#ifdef SQLITE_ENABLE_STAT3
    /* If the constraint is of the form x=VALUE or x IN (E1,E2,...)
    ** and we do not think that values of x are unique and if histogram
    ** data is available for column x, then it might be possible
    ** to get a better estimate on the number of rows based on
    ** VALUE and how common that value is according to the histogram.
    */
    if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 && aiRowEst[1]>1 ){
      assert( (pFirstTerm->eOperator & (WO_EQ|WO_ISNULL|WO_IN))!=0 );
      if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){
        testcase( pFirstTerm->eOperator==WO_EQ );
        testcase( pFirstTerm->eOperator==WO_ISNULL );
        whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow);
      }else if( bInEst==0 ){
        assert( pFirstTerm->eOperator==WO_IN );
        whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow);
      }
    }
#endif /* SQLITE_ENABLE_STAT3 */

    /* Adjust the number of output rows and downward to reflect rows
    ** that are excluded by range constraints.
    */
    nRow = nRow/rangeDiv;
    if( nRow<1 ) nRow = 1;

    /* Experiments run on real SQLite databases show that the time needed
    ** to do a binary search to locate a row in a table or index is roughly
    ** log10(N) times the time to move from one row to the next row within
    ** a table or index.  The actual times can vary, with the size of
    ** records being an important factor.  Both moves and searches are
    ** slower with larger records, presumably because fewer records fit
    ** on one page and hence more pages have to be fetched.
    **
    ** The ANALYZE command and the sqlite_stat1 and sqlite_stat3 tables do
    ** not give us data on the relative sizes of table and index records.
    ** So this computation assumes table records are about twice as big
    ** as index records
    */
    if( (wsFlags & WHERE_NOT_FULLSCAN)==0 ){
      /* The cost of a full table scan is a number of move operations equal
      ** to the number of rows in the table.
................................................................................
        }
      }
      if( nRow<2 ) nRow = 2;
    }


    WHERETRACE((
      "%s(%s): nEq=%d nInMul=%d rangeDiv=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
      "         notReady=0x%llx log10N=%.1f nRow=%.1f cost=%.1f used=0x%llx\n",
      pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), 
      nEq, nInMul, (int)rangeDiv, bSort, bLookup, wsFlags,
      notReady, log10N, nRow, cost, used
    ));

    /* If this index is the best we have seen so far, then record this
    ** index and its cost in the pCost structure.
    */
    if( (!pIdx || wsFlags)
................................................................................
** Generate code for the start of the iLevel-th loop in the WHERE clause
** implementation described by pWInfo.
*/
static Bitmask codeOneLoopStart(
  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
  int iLevel,          /* Which level of pWInfo->a[] should be coded */
  u16 wctrlFlags,      /* One of the WHERE_* flags defined in sqliteInt.h */
  Bitmask notReady,    /* Which tables are currently available */
  Expr *pWhere         /* Complete WHERE clause */
){
  int j, k;            /* Loop counters */
  int iCur;            /* The VDBE cursor for the table */
  int addrNxt;         /* Where to jump to continue with the next IN case */
  int omitTable;       /* True if we use the index only */
  int bRev;            /* True if we need to scan in reverse order */
  WhereLevel *pLevel;  /* The where level to be coded */
................................................................................

    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
    int regRowset = 0;                        /* Register for RowSet object */
    int regRowid = 0;                         /* Register holding rowid */
    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
    int iRetInit;                             /* Address of regReturn init */
    int untestedTerms = 0;             /* Some terms not completely tested */
    int ii;                            /* Loop counter */
    Expr *pAndExpr = 0;                /* An ".. AND (...)" expression */
   
    pTerm = pLevel->plan.u.pTerm;
    assert( pTerm!=0 );
    assert( pTerm->eOperator==WO_OR );
    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
    pOrWc = &pTerm->u.pOrInfo->wc;
    pLevel->op = OP_Return;
................................................................................
    */
    if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
      regRowset = ++pParse->nMem;
      regRowid = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
    }
    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);

    /* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
    ** Then for every term xN, evaluate as the subexpression: xN AND z
    ** That way, terms in y that are factored into the disjunction will
    ** be picked up by the recursive calls to sqlite3WhereBegin() below.
    */
    if( pWC->nTerm>1 ){
      pAndExpr = sqlite3ExprAlloc(pParse->db, TK_AND, 0, 0);
      pAndExpr->pRight = pWhere;
    }

    for(ii=0; ii<pOrWc->nTerm; ii++){
      WhereTerm *pOrTerm = &pOrWc->a[ii];
      if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){
        WhereInfo *pSubWInfo;          /* Info for single OR-term scan */
        Expr *pOrExpr = pOrTerm->pExpr;
        if( pAndExpr ){
          pAndExpr->pLeft = pOrExpr;
          pOrExpr = pAndExpr;
        }
        /* Loop through table entries that match term pOrTerm. */
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
                        WHERE_OMIT_OPEN_CLOSE | WHERE_AND_ONLY |
                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY);
        if( pSubWInfo ){
          explainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
................................................................................
          if( pSubWInfo->untestedTerms ) untestedTerms = 1;

          /* Finish the loop through table entries that match term pOrTerm. */
          sqlite3WhereEnd(pSubWInfo);
        }
      }
    }
    sqlite3DbFree(pParse->db, pAndExpr);
    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
    sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
    sqlite3VdbeResolveLabel(v, iLoopBody);

    if( pWInfo->nLevel>1 ) sqlite3StackFree(pParse->db, pOrTab);
    if( !untestedTerms ) disableTerm(pLevel, pTerm);
  }else
................................................................................
  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
  if( db->flags & SQLITE_DistinctOpt ) pDistinct = 0;

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(pWC, pParse, pMaskSet, wctrlFlags);
  sqlite3ExprCodeConstants(pParse, pWhere);
  whereSplit(pWC, pWhere, TK_AND);   /* IMP: R-15842-53296 */
    
  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  if( pWhere && (nTabList==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
................................................................................
      }
    }
    assert( bestJ>=0 );
    assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
    WHERETRACE(("*** Optimizer selects table %d for loop %d"
                " with cost=%g and nRow=%g\n",
                bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow));
    /* The ALWAYS() that follows was added to hush up clang scan-build */
    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 && ALWAYS(ppOrderBy) ){
      *ppOrderBy = 0;
    }
    if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){
      assert( pWInfo->eDistinct==0 );
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }
    andFlags &= bestPlan.plan.wsFlags;
................................................................................
    if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){
      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
      int iCur = pTabItem->iCursor;
      sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB);
    }else
#endif
    if( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0
         && (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 ){
      int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
      sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
      testcase( pTab->nCol==BMS-1 );
      testcase( pTab->nCol==BMS );
      if( !pWInfo->okOnePass && pTab->nCol<BMS ){
        Bitmask b = pTabItem->colUsed;
        int n = 0;
................................................................................
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(i=0; i<nTabList; i++){
    pLevel = &pWInfo->a[i];
    explainOneScan(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags);
    notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady, pWhere);
    pWInfo->iContinue = pLevel->addrCont;
  }

#ifdef SQLITE_TEST  /* For testing and debugging use only */
  /* Record in the query plan information about the current table
  ** and the index used to access it (if any).  If the table itself
  ** is not used, its name is just '{}'.  If no index is used
................................................................................
  assert( pWInfo->nLevel==1 || pWInfo->nLevel==pTabList->nSrc );
  for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
    struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
    Table *pTab = pTabItem->pTab;
    assert( pTab!=0 );
    if( (pTab->tabFlags & TF_Ephemeral)==0
     && pTab->pSelect==0
     && (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
    ){
      int ws = pLevel->plan.wsFlags;
      if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
        sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
      }
      if( (ws & WHERE_INDEXED)!=0 && (ws & WHERE_TEMP_INDEX)==0 ){
        sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
................................................................................
  void *yyp,                   /* The parser */
  int yymajor,                 /* The major token code number */
  sqlite3ParserTOKENTYPE yyminor       /* The value for the token */
  sqlite3ParserARG_PDECL               /* Optional %extra_argument parameter */
){
  YYMINORTYPE yyminorunion;
  int yyact;            /* The parser action. */
#if !defined(YYERRORSYMBOL) && !defined(YYNOERRORRECOVERY)
  int yyendofinput;     /* True if we are at the end of input */
#endif
#ifdef YYERRORSYMBOL
  int yyerrorhit = 0;   /* True if yymajor has invoked an error */
#endif
  yyParser *yypParser;  /* The parser */

  /* (re)initialize the parser, if necessary */
  yypParser = (yyParser*)yyp;
................................................................................
#endif
    yypParser->yyidx = 0;
    yypParser->yyerrcnt = -1;
    yypParser->yystack[0].stateno = 0;
    yypParser->yystack[0].major = 0;
  }
  yyminorunion.yy0 = yyminor;
#if !defined(YYERRORSYMBOL) && !defined(YYNOERRORRECOVERY)
  yyendofinput = (yymajor==0);
#endif
  sqlite3ParserARG_STORE;

#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sInput %s\n",yyTracePrompt,yyTokenName[yymajor]);
  }
#endif

  do{
    yyact = yy_find_shift_action(yypParser,(YYCODETYPE)yymajor);
    if( yyact<YYNSTATE ){

      yy_shift(yypParser,yyact,yymajor,&yyminorunion);
      yypParser->yyerrcnt--;
      yymajor = YYNOCODE;
    }else if( yyact < YYNSTATE + YYNRULE ){
      yy_reduce(yypParser,yyact-YYNSTATE);
    }else{
      assert( yyact == YY_ERROR_ACTION );
................................................................................
**    *  Calls to this routine from Y must block until the outer-most
**       call by X completes.
**
**    *  Recursive calls to this routine from thread X return immediately
**       without blocking.
*/
SQLITE_API int sqlite3_initialize(void){
  MUTEX_LOGIC( sqlite3_mutex *pMaster; )       /* The main static mutex */
  int rc;                                      /* Result code */

#ifdef SQLITE_OMIT_WSD
  rc = sqlite3_wsd_init(4096, 24);
  if( rc!=SQLITE_OK ){
    return rc;
  }
................................................................................

  /* Initialize the malloc() system and the recursive pInitMutex mutex.
  ** This operation is protected by the STATIC_MASTER mutex.  Note that
  ** MutexAlloc() is called for a static mutex prior to initializing the
  ** malloc subsystem - this implies that the allocation of a static
  ** mutex must not require support from the malloc subsystem.
  */
  MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
  sqlite3_mutex_enter(pMaster);
  sqlite3GlobalConfig.isMutexInit = 1;
  if( !sqlite3GlobalConfig.isMallocInit ){
    rc = sqlite3MallocInit();
  }
  if( rc==SQLITE_OK ){
    sqlite3GlobalConfig.isMallocInit = 1;
................................................................................
*/
SQLITE_API int sqlite3_overload_function(
  sqlite3 *db,
  const char *zName,
  int nArg
){
  int nName = sqlite3Strlen30(zName);
  int rc = SQLITE_OK;
  sqlite3_mutex_enter(db->mutex);
  if( sqlite3FindFunction(db, zName, nName, nArg, SQLITE_UTF8, 0)==0 ){
    rc = sqlite3CreateFunc(db, zName, nArg, SQLITE_UTF8,
                           0, sqlite3InvalidFunction, 0, 0, 0);
  }
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

#ifndef SQLITE_OMIT_TRACE
/*
** Register a trace function.  The pArg from the previously registered trace
................................................................................
opendb_out:
  sqlite3_free(zOpen);
  if( db ){
    assert( db->mutex!=0 || isThreadsafe==0 || sqlite3GlobalConfig.bFullMutex==0 );
    sqlite3_mutex_leave(db->mutex);
  }
  rc = sqlite3_errcode(db);
  assert( db!=0 || rc==SQLITE_NOMEM );
  if( rc==SQLITE_NOMEM ){
    sqlite3_close(db);
    db = 0;
  }else if( rc!=SQLITE_OK ){
    db->magic = SQLITE_MAGIC_SICK;
  }
  *ppDb = db;
................................................................................
#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
# define TESTONLY(X)  X
#else
# define TESTONLY(X)
#endif

#endif /* SQLITE_AMALGAMATION */

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3Fts3Corrupt(void);
# define FTS_CORRUPT_VTAB sqlite3Fts3Corrupt()
#else
# define FTS_CORRUPT_VTAB SQLITE_CORRUPT_VTAB
#endif

typedef struct Fts3Table Fts3Table;
typedef struct Fts3Cursor Fts3Cursor;
typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;
typedef struct Fts3PhraseToken Fts3PhraseToken;

................................................................................
  sqlite3_vtab base;              /* Base class used by SQLite core */
  sqlite3 *db;                    /* The database connection */
  const char *zDb;                /* logical database name */
  const char *zName;              /* virtual table name */
  int nColumn;                    /* number of named columns in virtual table */
  char **azColumn;                /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */
  char *zContentTbl;              /* content=xxx option, or NULL */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[27];

  char *zReadExprlist;
................................................................................
    int nPrefix;                  /* Prefix length (0 for main terms index) */
    Fts3Hash hPending;            /* Pending terms table for this index */
  } *aIndex;
  int nMaxPendingData;            /* Max pending data before flush to disk */
  int nPendingData;               /* Current bytes of pending data */
  sqlite_int64 iPrevDocid;        /* Docid of most recently inserted document */

#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
  /* State variables used for validating that the transaction control
  ** methods of the virtual table are called at appropriate times.  These
  ** values do not contribution to the FTS computation; they are used for
  ** verifying the SQLite core.
  */
  int inTransaction;     /* True after xBegin but before xCommit/xRollback */
  int mxSavepoint;       /* Largest valid xSavepoint integer */
................................................................................
** For a sequence of tokens contained in double-quotes (i.e. "one two three")
** nToken will be the number of tokens in the string.
*/
struct Fts3PhraseToken {
  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */
  int bFirst;                     /* True if token must appear at position 0 */

  /* Variables above this point are populated when the expression is
  ** parsed (by code in fts3_expr.c). Below this point the variables are
  ** used when evaluating the expression. */
  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
  Fts3MultiSegReader *pSegcsr;    /* Segment-reader for this token */
};
................................................................................

/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008
#define FTS3_SEGMENT_SCAN          0x00000010
#define FTS3_SEGMENT_FIRST         0x00000020

/* Type passed as 4th argument to SegmentReaderIterate() */
struct Fts3SegFilter {
  const char *zTerm;
  int nTerm;
  int iCol;
  int flags;
................................................................................
/* fts3.c */
SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *, sqlite3_int64);
SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64);
SQLITE_PRIVATE void sqlite3Fts3Dequote(char *);
SQLITE_PRIVATE void sqlite3Fts3DoclistPrev(int,char*,int,char**,sqlite3_int64*,int*,u8*);

SQLITE_PRIVATE int sqlite3Fts3EvalPhraseStats(Fts3Cursor *, Fts3Expr *, u32 *);
SQLITE_PRIVATE int sqlite3Fts3FirstFilter(sqlite3_int64, char *, int, char *);

/* fts3_tokenizer.c */
SQLITE_PRIVATE const char *sqlite3Fts3NextToken(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3InitHashTable(sqlite3 *, Fts3Hash *, const char *);
SQLITE_PRIVATE int sqlite3Fts3InitTokenizer(Fts3Hash *pHash, const char *, 
    sqlite3_tokenizer **, char **
);
................................................................................
SQLITE_PRIVATE void sqlite3Fts3Snippet(sqlite3_context *, Fts3Cursor *, const char *,
  const char *, const char *, int, int
);
SQLITE_PRIVATE void sqlite3Fts3Matchinfo(sqlite3_context *, Fts3Cursor *, const char *);

/* fts3_expr.c */
SQLITE_PRIVATE int sqlite3Fts3ExprParse(sqlite3_tokenizer *, 
  char **, int, int, int, const char *, int, Fts3Expr **
);
SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *);
#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
SQLITE_PRIVATE int sqlite3Fts3InitTerm(sqlite3 *db);
#endif

................................................................................
*/
static void fts3GetReverseVarint(
  char **pp, 
  char *pStart, 
  sqlite3_int64 *pVal
){
  sqlite3_int64 iVal;
  char *p;

  /* Pointer p now points at the first byte past the varint we are 
  ** interested in. So, unless the doclist is corrupt, the 0x80 bit is
  ** clear on character p[-1]. */
  for(p = (*pp)-2; p>=pStart && *p&0x80; p--);
  p++;
  *pp = p;
................................................................................
  /* Free any prepared statements held */
  for(i=0; i<SizeofArray(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }
  sqlite3_free(p->zSegmentsTbl);
  sqlite3_free(p->zReadExprlist);
  sqlite3_free(p->zWriteExprlist);
  sqlite3_free(p->zContentTbl);

  /* Invoke the tokenizer destructor to free the tokenizer. */
  p->pTokenizer->pModule->xDestroy(p->pTokenizer);

  sqlite3_free(p);
  return SQLITE_OK;
}
................................................................................
  }
}

/*
** The xDestroy() virtual table method.
*/
static int fts3DestroyMethod(sqlite3_vtab *pVtab){

  Fts3Table *p = (Fts3Table *)pVtab;
  int rc = SQLITE_OK;              /* Return code */
  const char *zDb = p->zDb;        /* Name of database (e.g. "main", "temp") */
  sqlite3 *db = p->db;             /* Database handle */

  /* Drop the shadow tables */
  if( p->zContentTbl==0 ){
    fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_content'", zDb, p->zName);
  }
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segments'", zDb,p->zName);
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segdir'", zDb, p->zName);
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_docsize'", zDb, p->zName);
  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_stat'", zDb, p->zName);

  /* If everything has worked, invoke fts3DisconnectMethod() to free the
  ** memory associated with the Fts3Table structure and return SQLITE_OK.
  ** Otherwise, return an SQLite error code.
  */
  return (rc==SQLITE_OK ? fts3DisconnectMethod(pVtab) : rc);
}
................................................................................
** If the p->bHasDocsize boolean is true (indicating that this is an
** FTS4 table, not an FTS3 table) then also create the %_docsize and
** %_stat tables required by FTS4.
*/
static int fts3CreateTables(Fts3Table *p){
  int rc = SQLITE_OK;             /* Return code */
  int i;                          /* Iterator variable */

  sqlite3 *db = p->db;            /* The database connection */

  if( p->zContentTbl==0 ){
    char *zContentCols;           /* Columns of %_content table */

    /* Create a list of user columns for the content table */
    zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
    for(i=0; zContentCols && i<p->nColumn; i++){
      char *z = p->azColumn[i];
      zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
    }
    if( zContentCols==0 ) rc = SQLITE_NOMEM;
  
    /* Create the content table */
    fts3DbExec(&rc, db, 
       "CREATE TABLE %Q.'%q_content'(%s)",
       p->zDb, p->zName, zContentCols
    );
    sqlite3_free(zContentCols);
  }

  /* Create other tables */
  fts3DbExec(&rc, db, 
      "CREATE TABLE %Q.'%q_segments'(blockid INTEGER PRIMARY KEY, block BLOB);",
      p->zDb, p->zName
  );
  fts3DbExec(&rc, db, 
      "CREATE TABLE %Q.'%q_segdir'("
................................................................................
    *(z++) = '"';
    *(z++) = '\0';
  }
  return zRet;
}

/*
** Return a list of comma separated SQL expressions and a FROM clause that 
** could be used in a SELECT statement such as the following:
**
**     SELECT <list of expressions> FROM %_content AS x ...
**
** to return the docid, followed by each column of text data in order
** from left to write. If parameter zFunc is not NULL, then instead of
** being returned directly each column of text data is passed to an SQL
** function named zFunc first. For example, if zFunc is "unzip" and the
** table has the three user-defined columns "a", "b", and "c", the following
** string is returned:
**
**     "docid, unzip(x.'a'), unzip(x.'b'), unzip(x.'c') FROM %_content AS x"
**
** The pointer returned points to a buffer allocated by sqlite3_malloc(). It
** is the responsibility of the caller to eventually free it.
**
** If *pRc is not SQLITE_OK when this function is called, it is a no-op (and
** a NULL pointer is returned). Otherwise, if an OOM error is encountered
** by this function, NULL is returned and *pRc is set to SQLITE_NOMEM. If
................................................................................
*/
static char *fts3ReadExprList(Fts3Table *p, const char *zFunc, int *pRc){
  char *zRet = 0;
  char *zFree = 0;
  char *zFunction;
  int i;

  if( p->zContentTbl==0 ){
    if( !zFunc ){
      zFunction = "";
    }else{
      zFree = zFunction = fts3QuoteId(zFunc);
    }
    fts3Appendf(pRc, &zRet, "docid");
    for(i=0; i<p->nColumn; i++){
      fts3Appendf(pRc, &zRet, ",%s(x.'c%d%q')", zFunction, i, p->azColumn[i]);
    }
    sqlite3_free(zFree);
  }else{
    fts3Appendf(pRc, &zRet, "rowid");
    for(i=0; i<p->nColumn; i++){
      fts3Appendf(pRc, &zRet, ", x.'%q'", p->azColumn[i]);
    }
  }
  fts3Appendf(pRc, &zRet, "FROM '%q'.'%q%s' AS x", 
      p->zDb,
      (p->zContentTbl ? p->zContentTbl : p->zName),
      (p->zContentTbl ? "" : "_content")
  );
  return zRet;
}

/*
** Return a list of N comma separated question marks, where N is the number
** of columns in the %_content table (one for the docid plus one for each
** user-defined text column).
................................................................................
**
** If *pp does not being with a decimal digit SQLITE_ERROR is returned and
** the output value undefined. Otherwise SQLITE_OK is returned.
**
** This function is used when parsing the "prefix=" FTS4 parameter.
*/
static int fts3GobbleInt(const char **pp, int *pnOut){
  const char *p;                  /* Iterator pointer */
  int nInt = 0;                   /* Output value */

  for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
    nInt = nInt * 10 + (p[0] - '0');
  }
  if( p==*pp ) return SQLITE_ERROR;
  *pnOut = nInt;
................................................................................
      aIndex[i].nPrefix = nPrefix;
      p++;
    }
  }

  return SQLITE_OK;
}

/*
** This function is called when initializing an FTS4 table that uses the
** content=xxx option. It determines the number of and names of the columns
** of the new FTS4 table.
**
** The third argument passed to this function is the value passed to the
** config=xxx option (i.e. "xxx"). This function queries the database for
** a table of that name. If found, the output variables are populated
** as follows:
**
**   *pnCol:   Set to the number of columns table xxx has,
**
**   *pnStr:   Set to the total amount of space required to store a copy
**             of each columns name, including the nul-terminator.
**
**   *pazCol:  Set to point to an array of *pnCol strings. Each string is
**             the name of the corresponding column in table xxx. The array
**             and its contents are allocated using a single allocation. It
**             is the responsibility of the caller to free this allocation
**             by eventually passing the *pazCol value to sqlite3_free().
**
** If the table cannot be found, an error code is returned and the output
** variables are undefined. Or, if an OOM is encountered, SQLITE_NOMEM is
** returned (and the output variables are undefined).
*/
static int fts3ContentColumns(
  sqlite3 *db,                    /* Database handle */
  const char *zDb,                /* Name of db (i.e. "main", "temp" etc.) */
  const char *zTbl,               /* Name of content table */
  const char ***pazCol,           /* OUT: Malloc'd array of column names */
  int *pnCol,                     /* OUT: Size of array *pazCol */
  int *pnStr                      /* OUT: Bytes of string content */
){
  int rc = SQLITE_OK;             /* Return code */
  char *zSql;                     /* "SELECT *" statement on zTbl */  
  sqlite3_stmt *pStmt = 0;        /* Compiled version of zSql */

  zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", zDb, zTbl);
  if( !zSql ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
  }
  sqlite3_free(zSql);

  if( rc==SQLITE_OK ){
    const char **azCol;           /* Output array */
    int nStr = 0;                 /* Size of all column names (incl. 0x00) */
    int nCol;                     /* Number of table columns */
    int i;                        /* Used to iterate through columns */

    /* Loop through the returned columns. Set nStr to the number of bytes of
    ** space required to store a copy of each column name, including the
    ** nul-terminator byte.  */
    nCol = sqlite3_column_count(pStmt);
    for(i=0; i<nCol; i++){
      const char *zCol = sqlite3_column_name(pStmt, i);
      nStr += strlen(zCol) + 1;
    }

    /* Allocate and populate the array to return. */
    azCol = (const char **)sqlite3_malloc(sizeof(char *) * nCol + nStr);
    if( azCol==0 ){
      rc = SQLITE_NOMEM;
    }else{
      char *p = (char *)&azCol[nCol];
      for(i=0; i<nCol; i++){
        const char *zCol = sqlite3_column_name(pStmt, i);
        int n = strlen(zCol)+1;
        memcpy(p, zCol, n);
        azCol[i] = p;
        p += n;
      }
    }
    sqlite3_finalize(pStmt);

    /* Set the output variables. */
    *pnCol = nCol;
    *pnStr = nStr;
    *pazCol = azCol;
  }

  return rc;
}

/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
................................................................................

  /* The results of parsing supported FTS4 key=value options: */
  int bNoDocsize = 0;             /* True to omit %_docsize table */
  int bDescIdx = 0;               /* True to store descending indexes */
  char *zPrefix = 0;              /* Prefix parameter value (or NULL) */
  char *zCompress = 0;            /* compress=? parameter (or NULL) */
  char *zUncompress = 0;          /* uncompress=? parameter (or NULL) */
  char *zContent = 0;             /* content=? parameter (or NULL) */

  assert( strlen(argv[0])==4 );
  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)
  );

  nDb = (int)strlen(argv[1]) + 1;
................................................................................
    }

    /* Check if it is an FTS4 special argument. */
    else if( isFts4 && fts3IsSpecialColumn(z, &nKey, &zVal) ){
      struct Fts4Option {
        const char *zOpt;
        int nOpt;
      } aFts4Opt[] = {
        { "matchinfo",   9 },     /* 0 -> MATCHINFO */
        { "prefix",      6 },     /* 1 -> PREFIX */
        { "compress",    8 },     /* 2 -> COMPRESS */
        { "uncompress", 10 },     /* 3 -> UNCOMPRESS */
        { "order",       5 },     /* 4 -> ORDER */
        { "content",     7 }      /* 5 -> CONTENT */
      };

      int iOpt;
      if( !zVal ){
        rc = SQLITE_NOMEM;
      }else{
        for(iOpt=0; iOpt<SizeofArray(aFts4Opt); iOpt++){
................................................................................
              sqlite3_free(zUncompress);
              zUncompress = zVal;
              zVal = 0;
              break;

            case 4:               /* ORDER */
              if( (strlen(zVal)!=3 || sqlite3_strnicmp(zVal, "asc", 3)) 
               && (strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "desc", 4)) 
              ){
                *pzErr = sqlite3_mprintf("unrecognized order: %s", zVal);
                rc = SQLITE_ERROR;
              }
              bDescIdx = (zVal[0]=='d' || zVal[0]=='D');
              break;

            default:              /* CONTENT */
              assert( iOpt==5 );
              sqlite3_free(zUncompress);
              zContent = zVal;
              zVal = 0;
              break;
          }
        }
        sqlite3_free(zVal);
      }
    }

    /* Otherwise, the argument is a column name. */
    else {
      nString += (int)(strlen(z) + 1);
      aCol[nCol++] = z;
    }
  }

  /* If a content=xxx option was specified, the following:
  **
  **   1. Ignore any compress= and uncompress= options.
  **
  **   2. If no column names were specified as part of the CREATE VIRTUAL
  **      TABLE statement, use all columns from the content table.
  */
  if( rc==SQLITE_OK && zContent ){
    sqlite3_free(zCompress); 
    sqlite3_free(zUncompress); 
    zCompress = 0;
    zUncompress = 0;
    if( nCol==0 ){
      sqlite3_free((void*)aCol); 
      aCol = 0;
      rc = fts3ContentColumns(db, argv[1], zContent, &aCol, &nCol, &nString);
    }
    assert( rc!=SQLITE_OK || nCol>0 );
  }
  if( rc!=SQLITE_OK ) goto fts3_init_out;

  if( nCol==0 ){
    assert( nString==0 );
    aCol[0] = "content";
    nString = 8;
    nCol = 1;
................................................................................
  p->nPendingData = 0;
  p->azColumn = (char **)&p[1];
  p->pTokenizer = pTokenizer;
  p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
  p->bHasDocsize = (isFts4 && bNoDocsize==0);
  p->bHasStat = isFts4;
  p->bDescIdx = bDescIdx;
  p->zContentTbl = zContent;
  zContent = 0;
  TESTONLY( p->inTransaction = -1 );
  TESTONLY( p->mxSavepoint = -1 );

  p->aIndex = (struct Fts3Index *)&p->azColumn[nCol];
  memcpy(p->aIndex, aIndex, sizeof(struct Fts3Index) * nIndex);
  p->nIndex = nIndex;
  for(i=0; i<nIndex; i++){
................................................................................
  fts3DeclareVtab(&rc, p);

fts3_init_out:
  sqlite3_free(zPrefix);
  sqlite3_free(aIndex);
  sqlite3_free(zCompress);
  sqlite3_free(zUncompress);
  sqlite3_free(zContent);
  sqlite3_free((void *)aCol);
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else if( pTokenizer ){
      pTokenizer->pModule->xDestroy(pTokenizer);
    }
................................................................................
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** If pCsr->pStmt has not been prepared (i.e. if pCsr->pStmt==0), then
** compose and prepare an SQL statement of the form:
**
**    "SELECT <columns> FROM %_content WHERE rowid = ?"
**
** (or the equivalent for a content=xxx table) and set pCsr->pStmt to
** it. If an error occurs, return an SQLite error code.
**
** Otherwise, set *ppStmt to point to pCsr->pStmt and return SQLITE_OK.
*/
static int fts3CursorSeekStmt(Fts3Cursor *pCsr, sqlite3_stmt **ppStmt){
  int rc = SQLITE_OK;
  if( pCsr->pStmt==0 ){
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
    char *zSql;
    zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
    if( !zSql ) return SQLITE_NOMEM;
    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);
  }
  *ppStmt = pCsr->pStmt;
  return rc;
}

/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
  int rc = SQLITE_OK;
  if( pCsr->isRequireSeek ){
    sqlite3_stmt *pStmt = 0;

    rc = fts3CursorSeekStmt(pCsr, &pStmt);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
      pCsr->isRequireSeek = 0;
      if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
        return SQLITE_OK;
      }else{
        rc = sqlite3_reset(pCsr->pStmt);
        if( rc==SQLITE_OK && ((Fts3Table *)pCsr->base.pVtab)->zContentTbl==0 ){
          /* If no row was found and no error has occured, then the %_content
          ** table is missing a row that is present in the full-text index.
          ** The data structures are corrupt.  */

          rc = FTS_CORRUPT_VTAB;

          pCsr->isEof = 1;
        }
      }
    }
  }

  if( rc!=SQLITE_OK && pContext ){
    sqlite3_result_error_code(pContext, rc);
  }
  return rc;




}

/*
** This function is used to process a single interior node when searching
** a b-tree for a term or term prefix. The node data is passed to this 
** function via the zNode/nNode parameters. The term to search for is
** passed in zTerm/nTerm.
................................................................................
  ** contents, or two zero bytes. Or, if the node is read from the %_segments
  ** table, then there are always 20 bytes of zeroed padding following the
  ** nNode bytes of content (see sqlite3Fts3ReadBlock() for details).
  */
  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  if( zCsr>zEnd ){
    return FTS_CORRUPT_VTAB;
  }
  
  while( zCsr<zEnd && (piFirst || piLast) ){
    int cmp;                      /* memcmp() result */
    int nSuffix;                  /* Size of term suffix */
    int nPrefix = 0;              /* Size of term prefix */
    int nBuffer;                  /* Total term size */
................................................................................
    if( !isFirstTerm ){
      zCsr += sqlite3Fts3GetVarint32(zCsr, &nPrefix);
    }
    isFirstTerm = 0;
    zCsr += sqlite3Fts3GetVarint32(zCsr, &nSuffix);
    
    if( nPrefix<0 || nSuffix<0 || &zCsr[nSuffix]>zEnd ){
      rc = FTS_CORRUPT_VTAB;
      goto finish_scan;
    }
    if( nPrefix+nSuffix>nAlloc ){
      char *zNew;
      nAlloc = (nPrefix+nSuffix) * 2;
      zNew = (char *)sqlite3_realloc(zBuffer, nAlloc);
      if( !zNew ){
        rc = SQLITE_NOMEM;
        goto finish_scan;
      }
      zBuffer = zNew;
    }
    assert( zBuffer );
    memcpy(&zBuffer[nPrefix], zCsr, nSuffix);
    nBuffer = nPrefix + nSuffix;
    zCsr += nSuffix;

    /* Compare the term we are searching for with the term just loaded from
    ** the interior node. If the specified term is greater than or equal
    ** to the term from the interior node, then all terms on the sub-tree 
................................................................................
  char **pp,                      /* IN/OUT: Preallocated output buffer */
  int nToken,                     /* Maximum difference in token positions */
  int isSaveLeft,                 /* Save the left position */
  int isExact,                    /* If *pp1 is exactly nTokens before *pp2 */
  char **pp1,                     /* IN/OUT: Left input list */
  char **pp2                      /* IN/OUT: Right input list */
){
  char *p = *pp;
  char *p1 = *pp1;
  char *p2 = *pp2;
  int iCol1 = 0;
  int iCol2 = 0;

  /* Never set both isSaveLeft and isExact for the same invocation. */
  assert( isSaveLeft==0 || isExact==0 );

  assert( p!=0 && *p1!=0 && *p2!=0 );
  if( *p1==POS_COLUMN ){ 
    p1++;
    p1 += sqlite3Fts3GetVarint32(p1, &iCol1);
  }
  if( *p2==POS_COLUMN ){ 
    p2++;
    p2 += sqlite3Fts3GetVarint32(p2, &iCol2);
................................................................................
  while( 1 ){
    if( iCol1==iCol2 ){
      char *pSave = p;
      sqlite3_int64 iPrev = 0;
      sqlite3_int64 iPos1 = 0;
      sqlite3_int64 iPos2 = 0;

      if( iCol1 ){
        *p++ = POS_COLUMN;
        p += sqlite3Fts3PutVarint(p, iCol1);
      }

      assert( *p1!=POS_END && *p1!=POS_COLUMN );
      assert( *p2!=POS_END && *p2!=POS_COLUMN );
      fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
................................................................................
      fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;

      while( 1 ){
        if( iPos2==iPos1+nToken 
         || (isExact==0 && iPos2>iPos1 && iPos2<=iPos1+nToken) 
        ){
          sqlite3_int64 iSave;







          iSave = isSaveLeft ? iPos1 : iPos2;
          fts3PutDeltaVarint(&p, &iPrev, iSave+2); iPrev -= 2;
          pSave = 0;
          assert( p );
        }
        if( (!isSaveLeft && iPos2<=(iPos1+nToken)) || iPos2<=iPos1 ){
          if( (*p2&0xFE)==0 ) break;
          fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;
        }else{
          if( (*p1&0xFE)==0 ) break;
          fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
................................................................................
    }
  }

  fts3PoslistCopy(0, &p2);
  fts3PoslistCopy(0, &p1);
  *pp1 = p1;
  *pp2 = p2;
  if( *pp==p ){
    return 0;
  }
  *p++ = 0x00;
  *pp = p;
  return 1;
}

................................................................................
      fts3PoslistCopy(0, &p2);
      fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
    }
  }

  *pnRight = p - aOut;
}

/*
** Argument pList points to a position list nList bytes in size. This
** function checks to see if the position list contains any entries for
** a token in position 0 (of any column). If so, it writes argument iDelta
** to the output buffer pOut, followed by a position list consisting only
** of the entries from pList at position 0, and terminated by an 0x00 byte.
** The value returned is the number of bytes written to pOut (if any).
*/
SQLITE_PRIVATE int sqlite3Fts3FirstFilter(
  sqlite3_int64 iDelta,           /* Varint that may be written to pOut */
  char *pList,                    /* Position list (no 0x00 term) */
  int nList,                      /* Size of pList in bytes */
  char *pOut                      /* Write output here */
){
  int nOut = 0;
  int bWritten = 0;               /* True once iDelta has been written */
  char *p = pList;
  char *pEnd = &pList[nList];

  if( *p!=0x01 ){
    if( *p==0x02 ){
      nOut += sqlite3Fts3PutVarint(&pOut[nOut], iDelta);
      pOut[nOut++] = 0x02;
      bWritten = 1;
    }
    fts3ColumnlistCopy(0, &p);
  }

  while( p<pEnd && *p==0x01 ){
    sqlite3_int64 iCol;
    p++;
    p += sqlite3Fts3GetVarint(p, &iCol);
    if( *p==0x02 ){
      if( bWritten==0 ){
        nOut += sqlite3Fts3PutVarint(&pOut[nOut], iDelta);
        bWritten = 1;
      }
      pOut[nOut++] = 0x01;
      nOut += sqlite3Fts3PutVarint(&pOut[nOut], iCol);
      pOut[nOut++] = 0x02;
    }
    fts3ColumnlistCopy(0, &p);
  }
  if( bWritten ){
    pOut[nOut++] = 0x00;
  }

  return nOut;
}


/*
** Merge all doclists in the TermSelect.aaOutput[] array into a single
** doclist stored in TermSelect.aaOutput[0]. If successful, delete all
** other doclists (except the aaOutput[0] one) and return SQLITE_OK.
**
................................................................................
  Fts3SegFilter filter;           /* Segment term filter configuration */

  pSegcsr = pTok->pSegcsr;
  memset(&tsc, 0, sizeof(TermSelect));

  filter.flags = FTS3_SEGMENT_IGNORE_EMPTY | FTS3_SEGMENT_REQUIRE_POS
        | (pTok->isPrefix ? FTS3_SEGMENT_PREFIX : 0)
        | (pTok->bFirst ? FTS3_SEGMENT_FIRST : 0)
        | (iColumn<p->nColumn ? FTS3_SEGMENT_COLUMN_FILTER : 0);
  filter.iCol = iColumn;
  filter.zTerm = pTok->z;
  filter.nTerm = pTok->n;

  rc = sqlite3Fts3SegReaderStart(p, pSegcsr, &filter);
  while( SQLITE_OK==rc
................................................................................
    int iCol = idxNum-FTS3_FULLTEXT_SEARCH;
    const char *zQuery = (const char *)sqlite3_value_text(apVal[0]);

    if( zQuery==0 && sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
      return SQLITE_NOMEM;
    }

    rc = sqlite3Fts3ExprParse(p->pTokenizer, p->azColumn, p->bHasStat, 
        p->nColumn, iCol, zQuery, -1, &pCsr->pExpr
    );
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_ERROR ){
        static const char *zErr = "malformed MATCH expression: [%s]";
        p->base.zErrMsg = sqlite3_mprintf(zErr, zQuery);
      }
      return rc;
................................................................................

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  if( idxNum==FTS3_FULLSCAN_SEARCH ){
    zSql = sqlite3_mprintf(
        "SELECT %s ORDER BY rowid %s",
        p->zReadExprlist, (pCsr->bDesc ? "DESC" : "ASC")



    );
    if( zSql ){



      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
      sqlite3_free(zSql);

    }else{
      rc = SQLITE_NOMEM;
    }
  }else if( idxNum==FTS3_DOCID_SEARCH ){
    rc = fts3CursorSeekStmt(pCsr, &pCsr->pStmt);
    if( rc==SQLITE_OK ){
      rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);

    }
  }
  if( rc!=SQLITE_OK ) return rc;

  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/
................................................................................
  }else if( iCol==p->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor.
    */
    sqlite3_result_blob(pContext, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);
  }else{
    rc = fts3CursorSeek(0, pCsr);
    if( rc==SQLITE_OK && sqlite3_data_count(pCsr->pStmt)>(iCol+1) ){
      sqlite3_result_value(pContext, sqlite3_column_value(pCsr->pStmt, iCol+1));
    }
  }

  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  return rc;
}
................................................................................
** When called, *ppPoslist must point to the byte immediately following the
** end of a position-list. i.e. ( (*ppPoslist)[-1]==POS_END ). This function
** moves *ppPoslist so that it instead points to the first byte of the
** same position list.
*/
static void fts3ReversePoslist(char *pStart, char **ppPoslist){
  char *p = &(*ppPoslist)[-2];
  char c = 0;

  while( p>pStart && (c=*p--)==0 );
  while( p>pStart && (*p & 0x80) | c ){ 
    c = *p--; 
  }
  if( p>pStart ){ p = &p[2]; }
  while( *p++&0x80 );
................................................................................
  sqlite3_vtab *pVtab,            /* Virtual table handle */
  const char *zName               /* New name of table */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  sqlite3 *db = p->db;            /* Database connection */
  int rc;                         /* Return Code */

  /* As it happens, the pending terms table is always empty here. This is
  ** because an "ALTER TABLE RENAME TABLE" statement inside a transaction 
  ** always opens a savepoint transaction. And the xSavepoint() method 
  ** flushes the pending terms table. But leave the (no-op) call to
  ** PendingTermsFlush() in in case that changes.
  */
  assert( p->nPendingData==0 );
  rc = sqlite3Fts3PendingTermsFlush(p);




  if( p->zContentTbl==0 ){
    fts3DbExec(&rc, db,
      "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';",
      p->zDb, p->zName, zName
    );
  }

  if( p->bHasDocsize ){
    fts3DbExec(&rc, db,
      "ALTER TABLE %Q.'%q_docsize'  RENAME TO '%q_docsize';",
      p->zDb, p->zName, zName
    );
  }
  if( p->bHasStat ){
................................................................................
** means that the phrase does not appear in the current row, doclist.pList
** and doclist.nList are both zeroed.
**
** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
*/
static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
  int iToken;                     /* Used to iterate through phrase tokens */

  char *aPoslist = 0;             /* Position list for deferred tokens */
  int nPoslist = 0;               /* Number of bytes in aPoslist */
  int iPrev = -1;                 /* Token number of previous deferred token */

  assert( pPhrase->doclist.bFreeList==0 );

  for(iToken=0; iToken<pPhrase->nToken; iToken++){
    Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
    Fts3DeferredToken *pDeferred = pToken->pDeferred;

    if( pDeferred ){
      char *pList;
      int nList;
      int rc = sqlite3Fts3DeferredTokenList(pDeferred, &pList, &nList);
      if( rc!=SQLITE_OK ) return rc;

      if( pList==0 ){
        sqlite3_free(aPoslist);
        pPhrase->doclist.pList = 0;
        pPhrase->doclist.nList = 0;
        return SQLITE_OK;
................................................................................
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;

  if( pCsr->bDesc==pTab->bDescIdx 
   && bOptOk==1 
   && p->nToken==1 
   && pFirst->pSegcsr 
   && pFirst->pSegcsr->bLookup 
   && pFirst->bFirst==0
  ){
    /* Use the incremental approach. */
    int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
    rc = sqlite3Fts3MsrIncrStart(
        pTab, pFirst->pSegcsr, iCol, pFirst->z, pFirst->n);
    p->bIncr = 1;

................................................................................
  Fts3Cursor *pCsr,               /* FTS Cursor handle */
  Fts3Expr *pRoot,                /* Root of current AND/NEAR cluster */
  Fts3Expr *pExpr,                /* Expression to consider */
  Fts3TokenAndCost **ppTC,        /* Write new entries to *(*ppTC)++ */
  Fts3Expr ***ppOr,               /* Write new OR root to *(*ppOr)++ */
  int *pRc                        /* IN/OUT: Error code */
){
  if( *pRc==SQLITE_OK ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      for(i=0; *pRc==SQLITE_OK && i<pPhrase->nToken; i++){
        Fts3TokenAndCost *pTC = (*ppTC)++;
        pTC->pPhrase = pPhrase;
        pTC->iToken = i;
        pTC->pRoot = pRoot;
        pTC->pToken = &pPhrase->aToken[i];
        pTC->iCol = pPhrase->iColumn;
        *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
      }
    }else if( pExpr->eType!=FTSQUERY_NOT ){
      assert( pExpr->eType==FTSQUERY_OR
           || pExpr->eType==FTSQUERY_AND
           || pExpr->eType==FTSQUERY_NEAR
      );
      assert( pExpr->pLeft && pExpr->pRight );
      if( pExpr->eType==FTSQUERY_OR ){
        pRoot = pExpr->pLeft;
        **ppOr = pRoot;
        (*ppOr)++;
      }
      fts3EvalTokenCosts(pCsr, pRoot, pExpr->pLeft, ppTC, ppOr, pRc);
      if( pExpr->eType==FTSQUERY_OR ){
................................................................................
    pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
    a += sqlite3Fts3GetVarint(a, &nDoc);
    while( a<pEnd ){
      a += sqlite3Fts3GetVarint(a, &nByte);
    }
    if( nDoc==0 || nByte==0 ){
      sqlite3_reset(pStmt);
      return FTS_CORRUPT_VTAB;
    }

    pCsr->nDoc = nDoc;
    pCsr->nRowAvg = (int)(((nByte / nDoc) + p->nPgsz) / p->nPgsz);
    assert( pCsr->nRowAvg>0 ); 
    rc = sqlite3_reset(pStmt);
    if( rc!=SQLITE_OK ) return rc;
................................................................................
  int rc = SQLITE_OK;             /* Return code */
  int ii;                         /* Iterator variable for various purposes */
  int nOvfl = 0;                  /* Total overflow pages used by doclists */
  int nToken = 0;                 /* Total number of tokens in cluster */

  int nMinEst = 0;                /* The minimum count for any phrase so far. */
  int nLoad4 = 1;                 /* (Phrases that will be loaded)^4. */

  /* Tokens are never deferred for FTS tables created using the content=xxx
  ** option. The reason being that it is not guaranteed that the content
  ** table actually contains the same data as the index. To prevent this from
  ** causing any problems, the deferred token optimization is completely
  ** disabled for content=xxx tables. */
  if( pTab->zContentTbl ){
    return SQLITE_OK;
  }

  /* Count the tokens in this AND/NEAR cluster. If none of the doclists
  ** associated with the tokens spill onto overflow pages, or if there is
  ** only 1 token, exit early. No tokens to defer in this case. */
  for(ii=0; ii<nTC; ii++){
    if( aTC[ii].pRoot==pRoot ){
      nOvfl += aTC[ii].nOvfl;
................................................................................
      ** that will be loaded if all subsequent tokens are deferred.
      */
      Fts3PhraseToken *pToken = pTC->pToken;
      rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
      fts3SegReaderCursorFree(pToken->pSegcsr);
      pToken->pSegcsr = 0;
    }else{
      /* Set nLoad4 to the value of (4^nOther) for the next iteration of the
      ** for-loop. Except, limit the value to 2^24 to prevent it from 
      ** overflowing the 32-bit integer it is stored in. */
      if( ii<12 ) nLoad4 = nLoad4*4;

      if( ii==0 || pTC->pPhrase->nToken>1 ){
        /* Either this is the cheapest token in the entire query, or it is
        ** part of a multi-token phrase. Either way, the entire doclist will
        ** (eventually) be loaded into memory. It may as well be now. */
        Fts3PhraseToken *pToken = pTC->pToken;
        int nList = 0;
        char *pList = 0;
................................................................................
        int nNear = p->nNear;
        res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
      }
  
      aPoslist = pExpr->pRight->pPhrase->doclist.pList;
      nToken = pExpr->pRight->pPhrase->nToken;
      for(p=pExpr->pLeft; p && res; p=p->pLeft){
        int nNear;
        Fts3Phrase *pPhrase;
        assert( p->pParent && p->pParent->pLeft==p );
        nNear = p->pParent->nNear;
        pPhrase = (
            p->eType==FTSQUERY_NEAR ? p->pRight->pPhrase : p->pPhrase
        );
        res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
      }
    }

    sqlite3_free(aTmp);
................................................................................
    for(i=0; i<pPhrase->nToken; i++){
      fts3SegReaderCursorFree(pPhrase->aToken[i].pSegcsr);
      pPhrase->aToken[i].pSegcsr = 0;
    }
  }
}

/*
** Return SQLITE_CORRUPT_VTAB.
*/
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3Fts3Corrupt(){
  return SQLITE_CORRUPT_VTAB;
}
#endif

#if !SQLITE_CORE
/*
** Initialize API pointer table, if required.
*/
SQLITE_API int sqlite3_extension_init(
  sqlite3 *db, 
  char **pzErrMsg,
................................................................................
**   FTS3 query "sqlite -mysql". Otherwise, ParseContext.isNot is set to
**   zero.
*/
typedef struct ParseContext ParseContext;
struct ParseContext {
  sqlite3_tokenizer *pTokenizer;      /* Tokenizer module */
  const char **azCol;                 /* Array of column names for fts3 table */
  int bFts4;                          /* True to allow FTS4-only syntax */
  int nCol;                           /* Number of entries in azCol[] */
  int iDefaultCol;                    /* Default column to query */
  int isNot;                          /* True if getNextNode() sees a unary - */
  sqlite3_context *pCtx;              /* Write error message here */
  int nNest;                          /* Number of nested brackets */
};

................................................................................
        pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
        memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);

        if( iEnd<n && z[iEnd]=='*' ){
          pRet->pPhrase->aToken[0].isPrefix = 1;
          iEnd++;
        }

        while( 1 ){
          if( !sqlite3_fts3_enable_parentheses 
           && iStart>0 && z[iStart-1]=='-' 
          ){
            pParse->isNot = 1;
            iStart--;
          }else if( pParse->bFts4 && iStart>0 && z[iStart-1]=='^' ){
            pRet->pPhrase->aToken[0].bFirst = 1;
            iStart--;
          }else{
            break;
          }
        }

      }
      nConsumed = iEnd;
    }

    pModule->xClose(pCursor);
  }
  
................................................................................
        memset(pToken, 0, sizeof(Fts3PhraseToken));

        memcpy(&zTemp[nTemp], zByte, nByte);
        nTemp += nByte;

        pToken->n = nByte;
        pToken->isPrefix = (iEnd<nInput && zInput[iEnd]=='*');
        pToken->bFirst = (iBegin>0 && zInput[iBegin-1]=='^');
        nToken = ii+1;
      }
    }

    pModule->xClose(pCursor);
    pCursor = 0;
  }
................................................................................
    memset(p, 0, (char *)&(((Fts3Phrase *)&p[1])->aToken[0])-(char *)p);
    p->eType = FTSQUERY_PHRASE;
    p->pPhrase = (Fts3Phrase *)&p[1];
    p->pPhrase->iColumn = pParse->iDefaultCol;
    p->pPhrase->nToken = nToken;

    zBuf = (char *)&p->pPhrase->aToken[nToken];
    if( zTemp ){
      memcpy(zBuf, zTemp, nTemp);
      sqlite3_free(zTemp);
    }else{
      assert( nTemp==0 );
    }

    for(jj=0; jj<p->pPhrase->nToken; jj++){
      p->pPhrase->aToken[jj].z = zBuf;
      zBuf += p->pPhrase->aToken[jj].n;
    }
    rc = SQLITE_OK;
  }
................................................................................
** column to match against for tokens for which a column name is not explicitly
** specified as part of the query string), or -1 if tokens may by default
** match any table column.
*/
SQLITE_PRIVATE int sqlite3Fts3ExprParse(
  sqlite3_tokenizer *pTokenizer,      /* Tokenizer module */
  char **azCol,                       /* Array of column names for fts3 table */
  int bFts4,                          /* True to allow FTS4-only syntax */
  int nCol,                           /* Number of entries in azCol[] */
  int iDefaultCol,                    /* Default column to query */
  const char *z, int n,               /* Text of MATCH query */
  Fts3Expr **ppExpr                   /* OUT: Parsed query structure */
){
  int nParsed;
  int rc;
  ParseContext sParse;
  sParse.pTokenizer = pTokenizer;
  sParse.azCol = (const char **)azCol;
  sParse.nCol = nCol;
  sParse.iDefaultCol = iDefaultCol;
  sParse.nNest = 0;
  sParse.bFts4 = bFts4;
  if( z==0 ){
    *ppExpr = 0;
    return SQLITE_OK;
  }
  if( n<0 ){
    n = (int)strlen(z);
  }
................................................................................
    goto exprtest_out;
  }
  for(ii=0; ii<nCol; ii++){
    azCol[ii] = (char *)sqlite3_value_text(argv[ii+2]);
  }

  rc = sqlite3Fts3ExprParse(
      pTokenizer, azCol, 0, nCol, nCol, zExpr, nExpr, &pExpr
  );
  if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM ){
    sqlite3_result_error(context, "Error parsing expression", -1);
  }else if( rc==SQLITE_NOMEM || !(zBuf = exprToString(pExpr, 0)) ){
    sqlite3_result_error_nomem(context);
  }else{
    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
................................................................................
/* 0  */  "DELETE FROM %Q.'%q_content' WHERE rowid = ?",
/* 1  */  "SELECT NOT EXISTS(SELECT docid FROM %Q.'%q_content' WHERE rowid!=?)",
/* 2  */  "DELETE FROM %Q.'%q_content'",
/* 3  */  "DELETE FROM %Q.'%q_segments'",
/* 4  */  "DELETE FROM %Q.'%q_segdir'",
/* 5  */  "DELETE FROM %Q.'%q_docsize'",
/* 6  */  "DELETE FROM %Q.'%q_stat'",
/* 7  */  "SELECT %s WHERE rowid=?",
/* 8  */  "SELECT (SELECT max(idx) FROM %Q.'%q_segdir' WHERE level = ?) + 1",
/* 9  */  "INSERT INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",

          /* Return segments in order from oldest to newest.*/ 
/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
................................................................................
  
  pStmt = p->aStmt[eStmt];
  if( !pStmt ){
    char *zSql;
    if( eStmt==SQL_CONTENT_INSERT ){
      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName, p->zWriteExprlist);
    }else if( eStmt==SQL_SELECT_CONTENT_BY_ROWID ){
      zSql = sqlite3_mprintf(azSql[eStmt], p->zReadExprlist);
    }else{
      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName);
    }
    if( !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, NULL);
................................................................................
  if( rc==SQLITE_OK ){
    if( eStmt==SQL_SELECT_DOCSIZE ){
      sqlite3_bind_int64(pStmt, 1, iDocid);
    }
    rc = sqlite3_step(pStmt);
    if( rc!=SQLITE_ROW || sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB ){
      rc = sqlite3_reset(pStmt);
      if( rc==SQLITE_OK ) rc = FTS_CORRUPT_VTAB;
      pStmt = 0;
    }else{
      rc = SQLITE_OK;
    }
  }

  *ppStmt = pStmt;
................................................................................
** write-locks on the %_segments and %_segdir ** tables). 
**
** We try to avoid this because if FTS3 returns any error when committing
** a transaction, the whole transaction will be rolled back. And this is
** not what users expect when they get SQLITE_LOCKED_SHAREDCACHE. It can
** still happen if the user reads data directly from the %_segments or
** %_segdir tables instead of going through FTS3 though.
**
** This reasoning does not apply to a content=xxx table.
*/
SQLITE_PRIVATE int sqlite3Fts3ReadLock(Fts3Table *p){
  int rc;                         /* Return code */
  sqlite3_stmt *pStmt;            /* Statement used to obtain lock */

  if( p->zContentTbl==0 ){
    rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pStmt, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_null(pStmt, 1);
      sqlite3_step(pStmt);
      rc = sqlite3_reset(pStmt);
    }
  }else{
    rc = SQLITE_OK;
  }

  return rc;
}

/*
** Set *ppStmt to a statement handle that may be used to iterate through
** all rows in the %_segdir table, from oldest to newest. If successful,
** return SQLITE_OK. If an error occurs while preparing the statement, 
................................................................................
static int fts3InsertData(
  Fts3Table *p,                   /* Full-text table */
  sqlite3_value **apVal,          /* Array of values to insert */
  sqlite3_int64 *piDocid          /* OUT: Docid for row just inserted */
){
  int rc;                         /* Return code */
  sqlite3_stmt *pContentInsert;   /* INSERT INTO %_content VALUES(...) */

  if( p->zContentTbl ){
    sqlite3_value *pRowid = apVal[p->nColumn+3];
    if( sqlite3_value_type(pRowid)==SQLITE_NULL ){
      pRowid = apVal[1];
    }
    if( sqlite3_value_type(pRowid)!=SQLITE_INTEGER ){
      return SQLITE_CONSTRAINT;
    }
    *piDocid = sqlite3_value_int64(pRowid);
    return SQLITE_OK;
  }

  /* Locate the statement handle used to insert data into the %_content
  ** table. The SQL for this statement is:
  **
  **   INSERT INTO %_content VALUES(?, ?, ?, ...)
  **
  ** The statement features N '?' variables, where N is the number of user
................................................................................



/*
** Remove all data from the FTS3 table. Clear the hash table containing
** pending terms.
*/
static int fts3DeleteAll(Fts3Table *p, int bContent){
  int rc = SQLITE_OK;             /* Return code */

  /* Discard the contents of the pending-terms hash table. */
  sqlite3Fts3PendingTermsClear(p);

  /* Delete everything from the shadow tables. Except, leave %_content as
  ** is if bContent is false.  */
  assert( p->zContentTbl==0 || bContent==0 );
  if( bContent ) fts3SqlExec(&rc, p, SQL_DELETE_ALL_CONTENT, 0);
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGMENTS, 0);
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
  if( p->bHasDocsize ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_DOCSIZE, 0);
  }
  if( p->bHasStat ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_STAT, 0);
................................................................................
  /* Because of the FTS3_NODE_PADDING bytes of padding, the following is 
  ** safe (no risk of overread) even if the node data is corrupted. */
  pNext += sqlite3Fts3GetVarint32(pNext, &nPrefix);
  pNext += sqlite3Fts3GetVarint32(pNext, &nSuffix);
  if( nPrefix<0 || nSuffix<=0 
   || &pNext[nSuffix]>&pReader->aNode[pReader->nNode] 
  ){
    return FTS_CORRUPT_VTAB;
  }

  if( nPrefix+nSuffix>pReader->nTermAlloc ){
    int nNew = (nPrefix+nSuffix)*2;
    char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
    if( !zNew ){
      return SQLITE_NOMEM;
................................................................................
  /* Check that the doclist does not appear to extend past the end of the
  ** b-tree node. And that the final byte of the doclist is 0x00. If either 
  ** of these statements is untrue, then the data structure is corrupt.
  */
  if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
   || (pReader->nPopulate==0 && pReader->aDoclist[pReader->nDoclist-1])
  ){
    return FTS_CORRUPT_VTAB;
  }
  return SQLITE_OK;
}

/*
** Set the SegReader to point to the first docid in the doclist associated
** with the current term.
................................................................................
** If successful, *pisEmpty is set to true if the table is empty except for
** document pRowid, or false otherwise, and SQLITE_OK is returned. If an
** error occurs, an SQLite error code is returned.
*/
static int fts3IsEmpty(Fts3Table *p, sqlite3_value *pRowid, int *pisEmpty){
  sqlite3_stmt *pStmt;
  int rc;
  if( p->zContentTbl ){
    /* If using the content=xxx option, assume the table is never empty */
    *pisEmpty = 0;
    rc = SQLITE_OK;
  }else{
    rc = fts3SqlStmt(p, SQL_IS_EMPTY, &pStmt, &pRowid);
    if( rc==SQLITE_OK ){
      if( SQLITE_ROW==sqlite3_step(pStmt) ){
        *pisEmpty = sqlite3_column_int(pStmt, 0);
      }
      rc = sqlite3_reset(pStmt);
    }
  }
  return rc;
}

/*
** Set *pnMax to the largest segment level in the database for the index
** iIndex.
................................................................................
  int rc = SQLITE_OK;

  int isIgnoreEmpty =  (pCsr->pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
  int isRequirePos =   (pCsr->pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
  int isColFilter =    (pCsr->pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
  int isPrefix =       (pCsr->pFilter->flags & FTS3_SEGMENT_PREFIX);
  int isScan =         (pCsr->pFilter->flags & FTS3_SEGMENT_SCAN);
  int isFirst =        (pCsr->pFilter->flags & FTS3_SEGMENT_FIRST);

  Fts3SegReader **apSegment = pCsr->apSegment;
  int nSegment = pCsr->nSegment;
  Fts3SegFilter *pFilter = pCsr->pFilter;
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );
................................................................................
    ){
      nMerge++;
    }

    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
    if( nMerge==1 
     && !isIgnoreEmpty 
     && !isFirst 
     && (p->bDescIdx==0 || fts3SegReaderIsPending(apSegment[0])==0)
    ){
      pCsr->nDoclist = apSegment[0]->nDoclist;
      if( fts3SegReaderIsPending(apSegment[0]) ){
        rc = fts3MsrBufferData(pCsr, apSegment[0]->aDoclist, pCsr->nDoclist);
        pCsr->aDoclist = pCsr->aBuffer;
      }else{
................................................................................
            pCsr->nBuffer = (nDoclist+nByte)*2;
            aNew = sqlite3_realloc(pCsr->aBuffer, pCsr->nBuffer);
            if( !aNew ){
              return SQLITE_NOMEM;
            }
            pCsr->aBuffer = aNew;
          }

          if( isFirst ){
            char *a = &pCsr->aBuffer[nDoclist];
            int nWrite;
           
            nWrite = sqlite3Fts3FirstFilter(iDelta, pList, nList, a);
            if( nWrite ){
              iPrev = iDocid;
              nDoclist += nWrite;
            }
          }else{
            nDoclist += sqlite3Fts3PutVarint(&pCsr->aBuffer[nDoclist], iDelta);
            iPrev = iDocid;
            if( isRequirePos ){
              memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
              nDoclist += nList;
              pCsr->aBuffer[nDoclist++] = '\0';
            }
          }
        }

        fts3SegReaderSort(apSegment, nMerge, j, xCmp);
      }
      if( nDoclist>0 ){
        pCsr->aDoclist = pCsr->aBuffer;
................................................................................

/*
** Insert the sizes (in tokens) for each column of the document
** with docid equal to p->iPrevDocid.  The sizes are encoded as
** a blob of varints.
*/
static void fts3InsertDocsize(
  int *pRC,                       /* Result code */
  Fts3Table *p,                   /* Table into which to insert */
  u32 *aSz                        /* Sizes of each column, in tokens */
){
  char *pBlob;             /* The BLOB encoding of the document size */
  int nBlob;               /* Number of bytes in the BLOB */
  sqlite3_stmt *pStmt;     /* Statement used to insert the encoding */
  int rc;                  /* Result code from subfunctions */

  if( *pRC ) return;
................................................................................
    }
  }
  sqlite3Fts3SegmentsClose(p);
  sqlite3Fts3PendingTermsClear(p);

  return (rc==SQLITE_OK && bReturnDone && bSeenDone) ? SQLITE_DONE : rc;
}

/*
** This function is called when the user executes the following statement:
**
**     INSERT INTO <tbl>(<tbl>) VALUES('rebuild');
**
** The entire FTS index is discarded and rebuilt. If the table is one 
** created using the content=xxx option, then the new index is based on
** the current contents of the xxx table. Otherwise, it is rebuilt based
** on the contents of the %_content table.
*/
static int fts3DoRebuild(Fts3Table *p){
  int rc;                         /* Return Code */

  rc = fts3DeleteAll(p, 0);
  if( rc==SQLITE_OK ){
    u32 *aSz = 0;
    u32 *aSzIns = 0;
    u32 *aSzDel = 0;
    sqlite3_stmt *pStmt = 0;
    int nEntry = 0;

    /* Compose and prepare an SQL statement to loop through the content table */
    char *zSql = sqlite3_mprintf("SELECT %s" , p->zReadExprlist);
    if( !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
      sqlite3_free(zSql);
    }

    if( rc==SQLITE_OK ){
      int nByte = sizeof(u32) * (p->nColumn+1)*3;
      aSz = (u32 *)sqlite3_malloc(nByte);
      if( aSz==0 ){
        rc = SQLITE_NOMEM;
      }else{
        memset(aSz, 0, nByte);
        aSzIns = &aSz[p->nColumn+1];
        aSzDel = &aSzIns[p->nColumn+1];
      }
    }

    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
      int iCol;
      rc = fts3PendingTermsDocid(p, sqlite3_column_int64(pStmt, 0));
      aSz[p->nColumn] = 0;
      for(iCol=0; rc==SQLITE_OK && iCol<p->nColumn; iCol++){
        const char *z = (const char *) sqlite3_column_text(pStmt, iCol+1);
        rc = fts3PendingTermsAdd(p, z, iCol, &aSz[iCol]);
        aSz[p->nColumn] += sqlite3_column_bytes(pStmt, iCol+1);
      }
      if( p->bHasDocsize ){
        fts3InsertDocsize(&rc, p, aSz);
      }
      if( rc!=SQLITE_OK ){
        sqlite3_finalize(pStmt);
        pStmt = 0;
      }else{
        nEntry++;
        for(iCol=0; iCol<=p->nColumn; iCol++){
          aSzIns[iCol] += aSz[iCol];
        }
      }
    }
    if( p->bHasStat ){
      fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nEntry);
    }
    sqlite3_free(aSz);

    if( pStmt ){
      int rc2 = sqlite3_finalize(pStmt);
      if( rc==SQLITE_OK ){
        rc = rc2;
      }
    }
  }

  return rc;
}

/*
** Handle a 'special' INSERT of the form:
**
**   "INSERT INTO tbl(tbl) VALUES(<expr>)"
**
** Argument pVal contains the result of <expr>. Currently the only 
................................................................................
  const char *zVal = (const char *)sqlite3_value_text(pVal);
  int nVal = sqlite3_value_bytes(pVal);

  if( !zVal ){
    return SQLITE_NOMEM;
  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
    rc = fts3DoOptimize(p, 0);
  }else if( nVal==7 && 0==sqlite3_strnicmp(zVal, "rebuild", 7) ){
    rc = fts3DoRebuild(p);
#ifdef SQLITE_TEST
  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
    p->nNodeSize = atoi(&zVal[9]);
    rc = SQLITE_OK;
  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
    p->nMaxPendingData = atoi(&zVal[11]);
    rc = SQLITE_OK;
................................................................................
        int iPos;                 /* Position of token in zText */
  
        pTC->pTokenizer = pT;
        rc = pModule->xNext(pTC, &zToken, &nToken, &iDum1, &iDum2, &iPos);
        for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
          Fts3PhraseToken *pPT = pDef->pToken;
          if( (pDef->iCol>=p->nColumn || pDef->iCol==i)
           && (pPT->bFirst==0 || iPos==0)
           && (pPT->n==nToken || (pPT->isPrefix && pPT->n<nToken))
           && (0==memcmp(zToken, pPT->z, pPT->n))
          ){
            fts3PendingListAppend(&pDef->pList, iDocid, i, iPos, &rc);
          }
        }
      }
................................................................................
  int isEmpty = 0;
  int rc = fts3IsEmpty(p, pRowid, &isEmpty);
  if( rc==SQLITE_OK ){
    if( isEmpty ){
      /* Deleting this row means the whole table is empty. In this case
      ** delete the contents of all three tables and throw away any
      ** data in the pendingTerms hash table.  */
      rc = fts3DeleteAll(p, 1);
      *pnDoc = *pnDoc - 1;
    }else{
      sqlite3_int64 iRemove = sqlite3_value_int64(pRowid);
      rc = fts3PendingTermsDocid(p, iRemove);
      fts3DeleteTerms(&rc, p, pRowid, aSzDel);
      if( p->zContentTbl==0 ){
        fts3SqlExec(&rc, p, SQL_DELETE_CONTENT, &pRowid);
        if( sqlite3_changes(p->db) ) *pnDoc = *pnDoc - 1;
      }else{
        *pnDoc = *pnDoc - 1;
      }
      if( p->bHasDocsize ){
        fts3SqlExec(&rc, p, SQL_DELETE_DOCSIZE, &pRowid);
      }
    }
  }

  return rc;
................................................................................
  int nArg,                       /* Size of argument array */
  sqlite3_value **apVal,          /* Array of arguments */
  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  int rc = SQLITE_OK;             /* Return Code */
  int isRemove = 0;               /* True for an UPDATE or DELETE */

  u32 *aSzIns = 0;                /* Sizes of inserted documents */
  u32 *aSzDel;                    /* Sizes of deleted documents */
  int nChng = 0;                  /* Net change in number of documents */
  int bInsertDone = 0;

  assert( p->pSegments==0 );

................................................................................
  **
  ** If the on-conflict mode is REPLACE, this means that the existing row
  ** should be deleted from the database before inserting the new row. Or,
  ** if the on-conflict mode is other than REPLACE, then this method must
  ** detect the conflict and return SQLITE_CONSTRAINT before beginning to
  ** modify the database file.
  */
  if( nArg>1 && p->zContentTbl==0 ){
    /* Find the value object that holds the new rowid value. */
    sqlite3_value *pNewRowid = apVal[3+p->nColumn];
    if( sqlite3_value_type(pNewRowid)==SQLITE_NULL ){
      pNewRowid = apVal[1];
    }

    if( sqlite3_value_type(pNewRowid)!=SQLITE_NULL && ( 
................................................................................
  }

  /* If this is a DELETE or UPDATE operation, remove the old record. */
  if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
    assert( sqlite3_value_type(apVal[0])==SQLITE_INTEGER );
    rc = fts3DeleteByRowid(p, apVal[0], &nChng, aSzDel);
    isRemove = 1;

  }
  
  /* If this is an INSERT or UPDATE operation, insert the new record. */
  if( nArg>1 && rc==SQLITE_OK ){
    if( bInsertDone==0 ){
      rc = fts3InsertData(p, apVal, pRowid);
      if( rc==SQLITE_CONSTRAINT && p->zContentTbl==0 ){
        rc = FTS_CORRUPT_VTAB;
      }
    }
    if( rc==SQLITE_OK && (!isRemove || *pRowid!=p->iPrevDocid ) ){
      rc = fts3PendingTermsDocid(p, *pRowid);
    }
    if( rc==SQLITE_OK ){
      assert( p->iPrevDocid==*pRowid );
      rc = fts3InsertTerms(p, apVal, aSzIns);
    }
    if( p->bHasDocsize ){
      fts3InsertDocsize(&rc, p, aSzIns);
    }
    nChng++;
  }
................................................................................
  pPhrase->nToken = pExpr->pPhrase->nToken;

  pCsr = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol);
  if( pCsr ){
    int iFirst = 0;
    pPhrase->pList = pCsr;
    fts3GetDeltaPosition(&pCsr, &iFirst);
    assert( iFirst>=0 );
    pPhrase->pHead = pCsr;
    pPhrase->pTail = pCsr;
    pPhrase->iHead = iFirst;
    pPhrase->iTail = iFirst;
  }else{
    assert( pPhrase->pList==0 && pPhrase->pHead==0 && pPhrase->pTail==0 );
  }
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  pStmt = *ppStmt;
  assert( sqlite3_data_count(pStmt)==1 );

  a = sqlite3_column_blob(pStmt, 0);
  a += sqlite3Fts3GetVarint(a, &nDoc);
  if( nDoc==0 ) return FTS_CORRUPT_VTAB;
  *pnDoc = (u32)nDoc;

  if( paLen ) *paLen = a;
  return SQLITE_OK;
}

/*
................................................................................
          iMinPos = pT->iPos-pT->iOff;
          pTerm = pT;
        }
      }

      if( !pTerm ){
        /* All offsets for this column have been gathered. */
        rc = SQLITE_DONE;
      }else{
        assert( iCurrent<=iMinPos );
        if( 0==(0xFE&*pTerm->pList) ){
          pTerm->pList = 0;
        }else{
          fts3GetDeltaPosition(&pTerm->pList, &pTerm->iPos);
        }
................................................................................
        }
        if( rc==SQLITE_OK ){
          char aBuffer[64];
          sqlite3_snprintf(sizeof(aBuffer), aBuffer, 
              "%d %d %d %d ", iCol, pTerm-sCtx.aTerm, iStart, iEnd-iStart
          );
          rc = fts3StringAppend(&res, aBuffer, -1);
        }else if( rc==SQLITE_DONE && pTab->zContentTbl==0 ){
          rc = FTS_CORRUPT_VTAB;
        }
      }
    }
    if( rc==SQLITE_DONE ){
      rc = SQLITE_OK;
    }

................................................................................
    if( argc>0 ){
      pCsr->aConstraint = sqlite3_malloc(sizeof(RtreeConstraint)*argc);
      pCsr->nConstraint = argc;
      if( !pCsr->aConstraint ){
        rc = SQLITE_NOMEM;
      }else{
        memset(pCsr->aConstraint, 0, sizeof(RtreeConstraint)*argc);
        assert( (idxStr==0 && argc==0)
                || (idxStr && (int)strlen(idxStr)==argc*2) );
        for(ii=0; ii<argc; ii++){
          RtreeConstraint *p = &pCsr->aConstraint[ii];
          p->op = idxStr[ii*2];
          p->iCoord = idxStr[ii*2+1]-'a';
          if( p->op==RTREE_MATCH ){
            /* A MATCH operator. The right-hand-side must be a blob that
            ** can be cast into an RtreeMatchArg object. One created using
................................................................................

  for(ii=0; rc==SQLITE_OK && ii<(pRtree->iDepth-iHeight); ii++){
    int iCell;
    sqlite3_int64 iBest = 0;

    float fMinGrowth = 0.0;
    float fMinArea = 0.0;
#if VARIANT_RSTARTREE_CHOOSESUBTREE
    float fMinOverlap = 0.0;
    float overlap;
#endif

    int nCell = NCELL(pNode);
    RtreeCell cell;
    RtreeNode *pChild;

    RtreeCell *aCell = 0;

................................................................................
    ** is inserted into it. Resolve ties by choosing the entry with
    ** the smallest area.
    */
    for(iCell=0; iCell<nCell; iCell++){
      int bBest = 0;
      float growth;
      float area;

      nodeGetCell(pRtree, pNode, iCell, &cell);
      growth = cellGrowth(pRtree, &cell, pCell);
      area = cellArea(pRtree, &cell);

#if VARIANT_RSTARTREE_CHOOSESUBTREE
      if( ii==(pRtree->iDepth-1) ){
        overlap = cellOverlapEnlargement(pRtree,&cell,pCell,aCell,nCell,iCell);
      }else{
        overlap = 0.0;
      }
      if( (iCell==0) 
       || (overlap<fMinOverlap) 
       || (overlap==fMinOverlap && growth<fMinGrowth)
       || (overlap==fMinOverlap && growth==fMinGrowth && area<fMinArea)
      ){
        bBest = 1;
        fMinOverlap = overlap;
      }
#else
      if( iCell==0||growth<fMinGrowth||(growth==fMinGrowth && area<fMinArea) ){
        bBest = 1;
      }
#endif
      if( bBest ){

        fMinGrowth = growth;
        fMinArea = area;
        iBest = cell.iRowid;
      }
    }

    sqlite3_free(aCell);

** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.8"
#define SQLITE_VERSION_NUMBER 3007008
#define SQLITE_SOURCE_ID      "2011-09-17 17:29:20 b31a7d7db9040d8eedaf1ecd89ea0033f579d0f1"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode.  If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
** 




*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7
#define SQLITE_FCNTL_SYNC_OMITTED     8
#define SQLITE_FCNTL_WIN32_AV_RETRY   9
#define SQLITE_FCNTL_PERSIST_WAL     10


/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
................................................................................
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.
** The minimum allocation size is capped at 2^12. Reasonable values
** for the minimum allocation size are 2^5 through 2^8.</dd>
**
** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
................................................................................
** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes.

**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
................................................................................
** WHERE clause might influence the choice of query plan for a statement,
** then the statement will be automatically recompiled, as if there had been 
** a schema change, on the first  [sqlite3_step()] call following any change
** to the [sqlite3_bind_text | bindings] of that [parameter]. 
** ^The specific value of WHERE-clause [parameter] might influence the 
** choice of query plan if the parameter is the left-hand side of a [LIKE]
** or [GLOB] operator or if the parameter is compared to an indexed column
** and the [SQLITE_ENABLE_STAT2] compile-time option is enabled.
** the 
** </li>
** </ol>
*/
SQLITE_API int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
................................................................................
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.







**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called
** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
** ^If the fifth argument is
................................................................................
**
** ^The sqlite3_data_count(P) interface returns the number of columns in the
** current row of the result set of [prepared statement] P.
** ^If prepared statement P does not have results ready to return
** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
** interfaces) then sqlite3_data_count(P) returns 0.
** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.






**
** See also: [sqlite3_column_count()]
*/
SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes
................................................................................
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.





** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not
................................................................................
**
** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
** <dd>This parameter returns the approximate number of of bytes of heap
** and lookaside memory used by all prepared statements associated with
** the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
** </dd>












** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
#define SQLITE_DBSTATUS_CACHE_USED           1
#define SQLITE_DBSTATUS_SCHEMA_USED          2
#define SQLITE_DBSTATUS_STMT_USED            3
#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6


#define SQLITE_DBSTATUS_MAX                  6   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS counters] that measure the number
................................................................................
**
** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
** <dd>^This is the number of rows inserted into transient indices that
** were created automatically in order to help joins run faster.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance by adding permanent indices that do not
** need to be reinitialized each time the statement is run.</dd>
**
** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2
#define SQLITE_STMTSTATUS_AUTOINDEX         3

/*

** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.9"
#define SQLITE_VERSION_NUMBER 3007009
#define SQLITE_SOURCE_ID      "2011-10-29 15:29:43 fb15f5458eb3e17ce9795c09bffe1224fea0eecd"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode.  If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
**
** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
** a write transaction to indicate that, unless it is rolled back for some
** reason, the entire database file will be overwritten by the current 
** transaction. This is used by VACUUM operations.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7
#define SQLITE_FCNTL_SYNC_OMITTED     8
#define SQLITE_FCNTL_WIN32_AV_RETRY   9
#define SQLITE_FCNTL_PERSIST_WAL     10
#define SQLITE_FCNTL_OVERWRITE       11

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
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** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.
** The minimum allocation size is capped at 2**12. Reasonable values
** for the minimum allocation size are 2**5 through 2**8.</dd>
**
** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
................................................................................
** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes as this saves SQLite from having to
** make a copy of the input string.
**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
................................................................................
** WHERE clause might influence the choice of query plan for a statement,
** then the statement will be automatically recompiled, as if there had been 
** a schema change, on the first  [sqlite3_step()] call following any change
** to the [sqlite3_bind_text | bindings] of that [parameter]. 
** ^The specific value of WHERE-clause [parameter] might influence the 
** choice of query plan if the parameter is the left-hand side of a [LIKE]
** or [GLOB] operator or if the parameter is compared to an indexed column
** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
** the 
** </li>
** </ol>
*/
SQLITE_API int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
................................................................................
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.
** If a non-negative fourth parameter is provided to sqlite3_bind_text()
** or sqlite3_bind_text16() then that parameter must be the byte offset
** where the NUL terminator would occur assuming the string were NUL
** terminated.  If any NUL characters occur at byte offsets less than 
** the value of the fourth parameter then the resulting string value will
** contain embedded NULs.  The result of expressions involving strings
** with embedded NULs is undefined.
**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called
** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
** ^If the fifth argument is
................................................................................
**
** ^The sqlite3_data_count(P) interface returns the number of columns in the
** current row of the result set of [prepared statement] P.
** ^If prepared statement P does not have results ready to return
** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
** interfaces) then sqlite3_data_count(P) returns 0.
** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
** will return non-zero if previous call to [sqlite3_step](P) returned
** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
** where it always returns zero since each step of that multi-step
** pragma returns 0 columns of data.
**
** See also: [sqlite3_column_count()]
*/
SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes
................................................................................
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.  If the 3rd parameter is non-negative, then it
** must be the byte offset into the string where the NUL terminator would
** appear if the string where NUL terminated.  If any NUL characters occur
** in the string at a byte offset that is less than the value of the 3rd
** parameter, then the resulting string will contain embedded NULs and the
** result of expressions operating on strings with embedded NULs is undefined.
** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not
................................................................................
**
** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
** <dd>This parameter returns the approximate number of of bytes of heap
** and lookaside memory used by all prepared statements associated with
** the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
** </dd>
**
** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
** <dd>This parameter returns the number of pager cache hits that have
** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT 
** is always 0.
** </dd>
**
** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
** <dd>This parameter returns the number of pager cache misses that have
** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS 
** is always 0.
** </dd>
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
#define SQLITE_DBSTATUS_CACHE_USED           1
#define SQLITE_DBSTATUS_SCHEMA_USED          2
#define SQLITE_DBSTATUS_STMT_USED            3
#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
#define SQLITE_DBSTATUS_CACHE_HIT            7
#define SQLITE_DBSTATUS_CACHE_MISS           8
#define SQLITE_DBSTATUS_MAX                  8   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS counters] that measure the number
................................................................................
**
** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
** <dd>^This is the number of rows inserted into transient indices that
** were created automatically in order to help joins run faster.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance by adding permanent indices that do not
** need to be reinitialized each time the statement is run.</dd>

** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2
#define SQLITE_STMTSTATUS_AUTOINDEX         3

/*