SQLite

/*
** 2003 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    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 used to implement the ATTACH and DETACH commands.
**
** $Id: attach.c,v 1.42 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"

/*
** Resolve an expression that was part of an ATTACH or DETACH statement. This
** is slightly different from resolving a normal SQL expression, because simple
** identifiers are treated as strings, not possible column names or aliases.

  ** or may not be initialised.
  */
  rc = sqlite3BtreeFactory(db, zFile, 0, MAX_PAGES, &aNew->pBt);
  if( rc==SQLITE_OK ){
    aNew->pSchema = sqlite3SchemaGet(aNew->pBt);
    if( !aNew->pSchema ){
      rc = SQLITE_NOMEM;
    }
    if( aNew->pSchema->file_format && aNew->pSchema->enc!=ENC(db) ){
      strcpy(zErr, 
        "attached databases must use the same text encoding as main database");
      goto attach_error;
    }
  }
  aNew->zName = sqliteStrDup(zName);
  aNew->safety_level = 3;

#if SQLITE_HAS_CODEC
  {

**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**
** $Id: build.c,v 1.372 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Initialize the pParse structure as needed.

  const char *zName
){
  int i;
  int nBytes;
  TableLock *p;
  ThreadData *pTsd = sqlite3ThreadData();

  if( 0==pTsd->useSharedData || iDb<0 ){
    return;
  }

  for(i=0; i<pParse->nTableLock; i++){
    p = &pParse->aTableLock[i];
    if( p->iDb==iDb && p->iTab==iTab ){
      p->isWriteLock = (p->isWriteLock || isWriteLock);

    ** set them now.
    */
    sqlite3VdbeAddOp(v, OP_ReadCookie, iDb, 1);   /* file_format */
    lbl = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp(v, OP_If, 0, lbl);
    sqlite3VdbeAddOp(v, OP_Integer, SQLITE_DEFAULT_FILE_FORMAT, 0);
    sqlite3VdbeAddOp(v, OP_SetCookie, iDb, 1);
    sqlite3VdbeAddOp(v, OP_Integer, ENC(db), 0);
    sqlite3VdbeAddOp(v, OP_SetCookie, iDb, 4);
    sqlite3VdbeResolveLabel(v, lbl);

    /* This just creates a place-holder record in the sqlite_master table.
    ** The record created does not contain anything yet.  It will be replaced
    ** by the real entry in code generated at sqlite3EndTable().
    **

**
** If no versions of the requested collations sequence are available, or
** another error occurs, NULL is returned and an error message written into
** pParse.
*/
CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char *zName, int nName){
  sqlite3 *db = pParse->db;
  u8 enc = ENC(db);
  u8 initbusy = db->init.busy;

  CollSeq *pColl = sqlite3FindCollSeq(db, enc, zName, nName, initbusy);
  if( !initbusy && (!pColl || !pColl->xCmp) ){
    pColl = sqlite3GetCollSeq(db, pColl, zName, nName);
    if( !pColl ){
      if( nName<0 ){

    int rc = sqlite3BtreeFactory(db, 0, 0, MAX_PAGES, &db->aDb[1].pBt);
    if( rc!=SQLITE_OK ){
      sqlite3ErrorMsg(pParse, "unable to open a temporary database "
        "file for storing temporary tables");
      pParse->rc = rc;
      return 1;
    }






    if( db->flags & !db->autoCommit ){
      rc = sqlite3BtreeBeginTrans(db->aDb[1].pBt, 1);
      if( rc!=SQLITE_OK ){
        sqlite3ErrorMsg(pParse, "unable to get a write lock on "
          "the temporary database file");
        pParse->rc = rc;
        return 1;
      }
    }
    assert( db->aDb[1].pSchema );
  }
  return 0;
}

/*
** Generate VDBE code that will verify the schema cookie and start
** a read-transaction for all named database files.

    return;
  }

  if( pName1==0 || pName1->z==0 ){
    reindexDatabases(pParse, 0);
    return;
  }else if( pName2==0 || pName2->z==0 ){
    pColl = sqlite3FindCollSeq(db, ENC(db), (char*)pName1->z, pName1->n, 0);
    if( pColl ){
      reindexDatabases(pParse, pColl);
      return;
    }
  }
  iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pObjName);
  if( iDb<0 ) return;

**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains functions used to access the internal hash tables
** of user defined functions and collation sequences.
**
** $Id: callback.c,v 1.9 2006/01/09 16:12:05 danielk1977 Exp $
*/

#include "sqliteInt.h"

/*
** Invoke the 'collation needed' callback to request a collation sequence
** in the database text encoding of name zName, length nName.
** If the collation sequence
*/
static void callCollNeeded(sqlite3 *db, const char *zName, int nName){
  assert( !db->xCollNeeded || !db->xCollNeeded16 );
  if( nName<0 ) nName = strlen(zName);
  if( db->xCollNeeded ){
    char *zExternal = sqliteStrNDup(zName, nName);
    if( !zExternal ) return;
    db->xCollNeeded(db->pCollNeededArg, db, (int)ENC(db), zExternal);
    sqliteFree(zExternal);
  }
#ifndef SQLITE_OMIT_UTF16
  if( db->xCollNeeded16 ){
    char const *zExternal;
    sqlite3_value *pTmp = sqlite3ValueNew();
    sqlite3ValueSetStr(pTmp, nName, zName, SQLITE_UTF8, SQLITE_STATIC);
    zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);
    if( zExternal ){
      db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);
    }
    sqlite3ValueFree(pTmp);
  }
#endif
}

/*

  const char *zName, 
  int nName
){
  CollSeq *p;

  p = pColl;
  if( !p ){
    p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);
  }
  if( !p || !p->xCmp ){
    /* No collation sequence of this type for this encoding is registered.
    ** Call the collation factory to see if it can supply us with one.
    */
    callCollNeeded(db, zName, nName);
    p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);
  }
  if( p && !p->xCmp && synthCollSeq(db, p) ){
    p = 0;
  }
  assert( !p || p->xCmp );
  return p;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.246 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**

      int no_such_func = 0;       /* True if no such function exists */
      int wrong_num_args = 0;     /* True if wrong number of arguments */
      int is_agg = 0;             /* True if is an aggregate function */
      int i;
      int nId;                    /* Number of characters in function name */
      const char *zId;            /* The function name. */
      FuncDef *pDef;              /* Information about the function */
      int enc = ENC(pParse->db);  /* The database encoding */

      zId = (char*)pExpr->token.z;
      nId = pExpr->token.n;
      pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);
      if( pDef==0 ){
        pDef = sqlite3FindFunction(pParse->db, zId, nId, -1, enc, 0);
        if( pDef==0 ){

      ExprList *pList = pExpr->pList;
      int nExpr = pList ? pList->nExpr : 0;
      FuncDef *pDef;
      int nId;
      const char *zId;
      int constMask = 0;
      int i;
      u8 enc = ENC(pParse->db);
      CollSeq *pColl = 0;
      zId = (char*)pExpr->token.z;
      nId = pExpr->token.n;
      pDef = sqlite3FindFunction(pParse->db, zId, nId, nExpr, enc, 0);
      assert( pDef!=0 );
      nExpr = sqlite3ExprCodeExprList(pParse, pList);
      for(i=0; i<nExpr && i<32; i++){

          if( sqlite3ExprCompare(pItem->pExpr, pExpr) ){
            break;
          }
        }
        if( i>=pAggInfo->nFunc ){
          /* pExpr is original.  Make a new entry in pAggInfo->aFunc[]
          */
          u8 enc = ENC(pParse->db);
          i = addAggInfoFunc(pAggInfo);
          if( i>=0 ){
            pItem = &pAggInfo->aFunc[i];
            pItem->pExpr = pExpr;
            pItem->iMem = pParse->nMem++;
            pItem->pFunc = sqlite3FindFunction(pParse->db,
                   (char*)pExpr->token.z, pExpr->token.n,

** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.115 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
/* #include <math.h> */
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"

  char *zVal;
  int len;
  sqlite3 *db = sqlite3_user_data(pCtx);
 
  test_destructor_count_var++;
  assert( nArg==1 );
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  len = sqlite3ValueBytes(argv[0], ENC(db)); 
  zVal = sqliteMalloc(len+3);
  zVal[len] = 0;
  zVal[len-1] = 0;
  assert( zVal );
  zVal++;
  memcpy(zVal, sqlite3ValueText(argv[0], ENC(db)), len);
  if( ENC(db)==SQLITE_UTF8 ){
    sqlite3_result_text(pCtx, zVal, -1, destructor);
#ifndef SQLITE_OMIT_UTF16
  }else if( ENC(db)==SQLITE_UTF16LE ){
    sqlite3_result_text16le(pCtx, zVal, -1, destructor);
  }else{
    sqlite3_result_text16be(pCtx, zVal, -1, destructor);
#endif /* SQLITE_OMIT_UTF16 */
  }
}
static void test_destructor_count(

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.320 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The following constant value is used by the SQLITE_BIGENDIAN and

  /* Allocate the sqlite data structure */
  db = sqliteMalloc( sizeof(sqlite3) );
  if( db==0 ) goto opendb_out;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;

  db->autoCommit = 1;
  db->flags |= SQLITE_ShortColNames;
  sqlite3HashInit(&db->aFunc, SQLITE_HASH_STRING, 0);
  sqlite3HashInit(&db->aCollSeq, SQLITE_HASH_STRING, 0);

#if 0
  for(i=0; i<db->nDb; i++){
    sqlite3HashInit(&db->aDb[i].tblHash, SQLITE_HASH_STRING, 0);
    sqlite3HashInit(&db->aDb[i].idxHash, SQLITE_HASH_STRING, 0);
    sqlite3HashInit(&db->aDb[i].trigHash, SQLITE_HASH_STRING, 0);
    sqlite3HashInit(&db->aDb[i].aFKey, SQLITE_HASH_STRING, 1);
  }
#endif
 
  /* Add the default collation sequence BINARY. BINARY works for both UTF-8
  ** and UTF-16, so add a version for each to avoid any unnecessary
  ** conversions. The only error that can occur here is a malloc() failure.
  */
  if( sqlite3_create_collation(db, "BINARY", SQLITE_UTF8, 0,binCollFunc) ||
      sqlite3_create_collation(db, "BINARY", SQLITE_UTF16, 0,binCollFunc) ||
      (db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, "BINARY", 6, 0))==0 
  ){
    /* sqlite3_create_collation() is an external API. So the mallocFailed flag
    ** will have been cleared before returning. So set it explicitly here.
    */
    sqlite3ThreadData()->mallocFailed = 1;
    db->magic = SQLITE_MAGIC_CLOSED;
    goto opendb_out;

    db->magic = SQLITE_MAGIC_CLOSED;
    goto opendb_out;
  }
#ifndef SQLITE_OMIT_PARSER
  db->aDb[0].pSchema = sqlite3SchemaGet(db->aDb[0].pBt);
  db->aDb[1].pSchema = sqlite3SchemaGet(0);
#endif

  if( db->aDb[0].pSchema ){
    ENC(db) = SQLITE_UTF8;
  }

  /* The default safety_level for the main database is 'full'; for the temp
  ** database it is 'NONE'. This matches the pager layer defaults.  
  */
  db->aDb[0].zName = "main";
  db->aDb[0].safety_level = 3;
#ifndef SQLITE_OMIT_TEMPDB

/*
** 2003 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    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 used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.111 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/

      sqlite3BeginWriteOperation(pParse, 0, iDb);
      sqlite3VdbeAddOp(v, OP_Integer, size, 0);
      sqlite3VdbeAddOp(v, OP_ReadCookie, iDb, 2);
      addr = sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
      sqlite3VdbeAddOp(v, OP_Ge, 0, addr+3);
      sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
      sqlite3VdbeAddOp(v, OP_SetCookie, iDb, 2);
      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
  }else

  /*
  **  PRAGMA [database.]page_size
  **  PRAGMA [database.]page_size=N
  **

  ** cache size stored on the disk so the cache size will revert
  ** to its default value when the database is closed and reopened.
  ** N should be a positive integer.
  */
  if( sqlite3StrICmp(zLeft,"cache_size")==0 ){
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
    if( !zRight ){
      returnSingleInt(pParse, "cache_size", pDb->pSchema->cache_size);
    }else{
      int size = atoi(zRight);
      if( size<0 ) size = -size;
      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
  }else

  /*
  **   PRAGMA temp_store
  **   PRAGMA temp_store = "default"|"memory"|"file"
  **

    encnames[6].enc = encnames[7].enc = SQLITE_UTF16NATIVE;
    if( !zRight ){    /* "PRAGMA encoding" */
      if( sqlite3ReadSchema(pParse) ) goto pragma_out;
      sqlite3VdbeSetNumCols(v, 1);
      sqlite3VdbeSetColName(v, 0, "encoding", P3_STATIC);
      sqlite3VdbeAddOp(v, OP_String8, 0, 0);
      for(pEnc=&encnames[0]; pEnc->zName; pEnc++){
        if( pEnc->enc==ENC(pParse->db) ){
          sqlite3VdbeChangeP3(v, -1, pEnc->zName, P3_STATIC);
          break;
        }
      }
      sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    }else{                        /* "PRAGMA encoding = XXX" */
      /* Only change the value of sqlite.enc if the database handle is not
      ** initialized. If the main database exists, the new sqlite.enc value
      ** will be overwritten when the schema is next loaded. If it does not
      ** already exists, it will be created to use the new encoding value.
      */
      if( !(pParse->db->flags&SQLITE_Initialized) ){
        for(pEnc=&encnames[0]; pEnc->zName; pEnc++){
          if( 0==sqlite3StrICmp(zRight, pEnc->zName) ){
            ENC(pParse->db) = pEnc->enc;
            break;
          }
        }
        if( !pEnc->zName ){
          sqlite3ErrorMsg(pParse, "unsupported encoding: %s", zRight);
        }
      }

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_prepare()
** interface, and routines that contribute to loading the database schema
** from disk.
**
** $Id: prepare.c,v 1.17 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** Fill the InitData structure with an error message that indicates

  ;
#else
  #define temp_master_schema 0
#endif

  assert( iDb>=0 && iDb<db->nDb );

  assert( db->aDb[iDb].pSchema );
#if 0
  if( 0==db->aDb[iDb].pSchema ){

    Schema *pS = sqlite3SchemaGet(db->aDb[iDb].pBt);
    db->aDb[iDb].pSchema = pS;
    if( !pS ){
      return SQLITE_NOMEM;
    }else if( pS->file_format!=0 ){
      /* This means that the shared-schema associated with the the btree
      ** is already open and populated.
      */
      if( pS->enc!=ENC(db) ){
        sqlite3SetString(pzErrMsg, "attached databases must use the same"
            " text encoding as main database", (char*)0);
        return SQLITE_ERROR;




      }
      return SQLITE_OK;
    }
  }
#endif

  /* zMasterSchema and zInitScript are set to point at the master schema
  ** and initialisation script appropriate for the database being
  ** initialised. zMasterName is the name of the master table.
  */
  if( !OMIT_TEMPDB && iDb==1 ){
    zMasterSchema = temp_master_schema;

  /* If opening a non-empty database, check the text encoding. For the
  ** main database, set sqlite3.enc to the encoding of the main database.
  ** For an attached db, it is an error if the encoding is not the same
  ** as sqlite3.enc.
  */
  if( meta[4] ){  /* text encoding */
    if( iDb==0 ){
      /* If opening the main database, set ENC(db). */
      ENC(db) = (u8)meta[4];
      db->pDfltColl = sqlite3FindCollSeq(db, ENC(db), "BINARY", 6, 0);
    }else{
      /* If opening an attached database, the encoding much match ENC(db) */
      if( meta[4]!=ENC(db) ){
        sqlite3BtreeCloseCursor(curMain);
        sqlite3SetString(pzErrMsg, "attached databases must use the same"
            " text encoding as main database", (char*)0);
        return SQLITE_ERROR;
      }
    }
  }
  pDb->pSchema->enc = ENC(db);

  size = meta[2];
  if( size==0 ){ size = MAX_PAGES; }
  pDb->pSchema->cache_size = size;
  sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);

  /*
  ** file_format==1    Version 3.0.0.
  ** file_format==2    Version 3.1.3.  // ALTER TABLE ADD COLUMN
  ** file_format==3    Version 3.1.4.  // ditto but with non-NULL defaults
  ** file_format==4    Version 3.3.0.  // DESC indices.  Boolean constants
  */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.291 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.

  int i;

  nExpr = pList->nExpr;
  pInfo = sqliteMalloc( sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
  if( pInfo ){
    pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
    pInfo->nField = nExpr;
    pInfo->enc = ENC(db);
    for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
      CollSeq *pColl;
      pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
      if( !pColl ){
        pColl = db->pDfltColl;
      }
      pInfo->aColl[i] = pColl;

    assert( p->pRightmost==p );
    pKeyInfo = sqliteMalloc(sizeof(*pKeyInfo)+nCol*2*sizeof(CollSeq*) + nCol);
    if( !pKeyInfo ){
      rc = SQLITE_NOMEM;
      goto multi_select_end;
    }

    pKeyInfo->enc = ENC(pParse->db);
    pKeyInfo->nField = nCol;

    for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
      *apColl = multiSelectCollSeq(pParse, p, i);
      if( 0==*apColl ){
        *apColl = pParse->db->pDfltColl;
      }

  /* Generating code to find the min or the max.  Basically all we have
  ** to do is find the first or the last entry in the chosen index.  If
  ** the min() or max() is on the INTEGER PRIMARY KEY, then find the first
  ** or last entry in the main table.
  */
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  assert( iDb>=0 || pTab->isTransient );
  sqlite3CodeVerifySchema(pParse, iDb);
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
  base = pSrc->a[0].iCursor;
  brk = sqlite3VdbeMakeLabel(v);
  computeLimitRegisters(pParse, p, brk);
  if( pSrc->a[0].pSelect==0 ){
    sqlite3OpenTable(pParse, base, iDb, pTab, OP_OpenRead);

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.456 2006/01/09 16:12:05 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Extra interface definitions for those who need them
*/

** databases may be attached.
*/
struct Db {
  char *zName;         /* Name of this database */
  Btree *pBt;          /* The B*Tree structure for this database file */
  u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
  u8 safety_level;     /* How aggressive at synching data to disk */

  void *pAux;               /* Auxiliary data.  Usually NULL */
  void (*xFreeAux)(void*);  /* Routine to free pAux */
  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
};

/*
** An instance of the following structure stores a database schema.
*/
struct Schema {
  int schema_cookie;   /* Database schema version number for this file */
  Hash tblHash;        /* All tables indexed by name */
  Hash idxHash;        /* All (named) indices indexed by name */
  Hash trigHash;       /* All triggers indexed by name */
  Hash aFKey;          /* Foreign keys indexed by to-table */
  Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
  u8 file_format;      /* Schema format version for this file */
  u16 flags;           /* Flags associated with this schema */
  int cache_size;      /* Number of pages to use in the cache */
  u8 enc;              /* Text encoding used by this database */
};

/*
** These macros can be used to test, set, or clear bits in the 
** Db.flags field.
*/
#define DbHasProperty(D,I,P)     (((D)->aDb[I].pSchema->flags&(P))==(P))

** consistently.
*/
struct sqlite3 {
  int nDb;                      /* Number of backends currently in use */
  Db *aDb;                      /* All backends */
  int flags;                    /* Miscellanous flags. See below */
  int errCode;                  /* Most recent error code (SQLITE_*) */

  u8 autoCommit;                /* The auto-commit flag. */
  u8 temp_store;                /* 1: file 2: memory 0: default */
  int nTable;                   /* Number of tables in the database */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 priorNewRowid;            /* Last randomly generated ROWID */
  int magic;                    /* Magic number for detect library misuse */

  BusyHandler busyHandler;      /* Busy callback */
  int busyTimeout;             /* Busy handler timeout, in msec */
  Db aDbStatic[2];              /* Static space for the 2 default backends */
#ifdef SQLITE_SSE
  sqlite3_stmt *pFetch;         /* Used by SSE to fetch stored statements */
#endif
};

#define ENC(db) ((db)->aDb[0].pSchema->enc)

/*
** Possible values for the sqlite.flags and or Db.flags fields.
**
** On sqlite.flags, the SQLITE_InTrans value means that we have
** executed a BEGIN.  On Db.flags, SQLITE_InTrans means a statement
** transaction is active on that particular database file.

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the printf() interface to SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.186 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

*/
static void test_collate_needed_cb(
  void *pCtx, 
  sqlite3 *db,
  int eTextRep,
  const void *pName
){
  int enc = ENC(db);
  int i;
  char *z;
  for(z = (char*)pName, i=0; *z || z[1]; z++){
    if( *z ) zNeededCollation[i++] = *z;
  }
  zNeededCollation[i] = 0;
  sqlite3_create_collation(
      db, "test_collate", ENC(db), (void *)enc, test_collate_func);
}

/*
** Usage: add_test_collate_needed DB
*/
static int test_collate_needed(
  void * clientData,

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.118 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"

/*
** The most recently coded instruction was an OP_Column to retrieve the
** i-th column of table pTab. This routine sets the P3 parameter of the 
** OP_Column to the default value, if any.

** the column is a literal number, string or null. The sqlite3ValueFromExpr()
** function is capable of transforming these types of expressions into
** sqlite3_value objects.
*/
void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i){
  if( pTab && !pTab->pSelect ){
    sqlite3_value *pValue;
    u8 enc = ENC(sqlite3VdbeDb(v));
    Column *pCol = &pTab->aCol[i];
    sqlite3ValueFromExpr(pCol->pDflt, enc, pCol->affinity, &pValue);
    if( pValue ){
      sqlite3VdbeChangeP3(v, -1, (const char *)pValue, P3_MEM);
    }else{
      VdbeComment((v, "# %s.%s", pTab->zName, pCol->zName));
    }

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.520 2006/01/09 16:12:05 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

  pTos++;
  pTos->flags = MEM_Str|MEM_Static|MEM_Term;
  pTos->z = pOp->p3;
  pTos->n = strlen(pTos->z);
  pTos->enc = SQLITE_UTF8;
  pTos->r = sqlite3VdbeRealValue(pTos);
  pTos->flags |= MEM_Real;
  sqlite3VdbeChangeEncoding(pTos, ENC(db));
  break;
}

/* Opcode: String8 * * P3
**
** P3 points to a nul terminated UTF-8 string that is P1 character long
** (not counting the nul terminator). This opcode is transformed
** into an OP_String before it is executed for the first time.
*/
case OP_String8: {         /* same as TK_STRING */
  assert( pOp->p3!=0 );
  pOp->opcode = OP_String;
  pOp->p1 = strlen(pOp->p3);

#ifndef SQLITE_OMIT_UTF16
  if( ENC(db)!=SQLITE_UTF8 ){
    pTos++;
    sqlite3VdbeMemSetStr(pTos, pOp->p3, -1, SQLITE_UTF8, SQLITE_STATIC);
    if( SQLITE_OK!=sqlite3VdbeChangeEncoding(pTos, ENC(db)) ) goto no_mem;
    if( SQLITE_OK!=sqlite3VdbeMemDynamicify(pTos) ) goto no_mem;
    pTos->flags &= ~(MEM_Dyn);
    pTos->flags |= MEM_Static;
    if( pOp->p3type==P3_DYNAMIC ){
      sqliteFree(pOp->p3);
    }
    pOp->p3type = P3_DYNAMIC;

*/
case OP_String: {
  pTos++;
  assert( pOp->p3!=0 );
  pTos->flags = MEM_Str|MEM_Static|MEM_Term;
  pTos->z = pOp->p3;
  pTos->n = pOp->p1;
  pTos->enc = ENC(db);
  break;
}

/* Opcode: Null * * *
**
** Push a NULL onto the stack.
*/

  /* Make sure the results of the current row are \000 terminated
  ** and have an assigned type.  The results are deephemeralized as
  ** as side effect.
  */
  for(; pMem<=pTos; pMem++ ){
    sqlite3VdbeMemNulTerminate(pMem);
    storeTypeInfo(pMem, ENC(db));
  }

  /* Set up the statement structure so that it will pop the current
  ** results from the stack when the statement returns.
  */
  p->resOnStack = 1;
  p->nCallback++;

  nByte = 0;
  for(i=0; i<nField; i++, pTerm++){
    assert( pOp->p2==0 || (pTerm->flags&MEM_Str) );
    if( pTerm->flags&MEM_Null ){
      nByte = -1;
      break;
    }
    Stringify(pTerm, ENC(db));
    nByte += pTerm->n;
  }

  if( nByte<0 ){
    /* If nByte is less than zero, then there is a NULL value on the stack.
    ** In this case just pop the values off the stack (if required) and
    ** push on a NULL.

    if( pOp->p2==0 ){
      popStack(&pTos, nField);
    }
    pTos++;
    pTos->n = j;
    pTos->flags = MEM_Str|MEM_Dyn|MEM_Term;
    pTos->xDel = 0;
    pTos->enc = ENC(db);
    pTos->z = zNew;
  }
  break;
}

/* Opcode: Add * * *
**

  apVal = p->apArg;
  assert( apVal || n==0 );

  pArg = &pTos[1-n];
  for(i=0; i<n; i++, pArg++){
    apVal[i] = pArg;
    storeTypeInfo(pArg, ENC(db));
  }

  assert( pOp->p3type==P3_FUNCDEF || pOp->p3type==P3_VDBEFUNC );
  if( pOp->p3type==P3_FUNCDEF ){
    ctx.pFunc = (FuncDef*)pOp->p3;
    ctx.pVdbeFunc = 0;
  }else{

  if( ctx.pVdbeFunc ){
    sqlite3VdbeDeleteAuxData(ctx.pVdbeFunc, pOp->p1);
    pOp->p3 = (char *)ctx.pVdbeFunc;
    pOp->p3type = P3_VDBEFUNC;
  }

  /* Copy the result of the function to the top of the stack */
  sqlite3VdbeChangeEncoding(&ctx.s, ENC(db));
  pTos++;
  pTos->flags = 0;
  sqlite3VdbeMemMove(pTos, &ctx.s);

  /* If the function returned an error, throw an exception */
  if( ctx.isError ){
    if( !(pTos->flags&MEM_Str) ){
      sqlite3SetString(&p->zErrMsg, "user function error", (char*)0);
    }else{
      sqlite3SetString(&p->zErrMsg, sqlite3_value_text(pTos), (char*)0);
      sqlite3VdbeChangeEncoding(pTos, ENC(db));
    }
    rc = SQLITE_ERROR;
  }
  break;
}

/* Opcode: BitAnd * * *

** convert it into the least integer that is greater than or equal to its
** current value if P1==0, or to the least integer that is strictly
** greater than its current value if P1==1.
*/
case OP_ForceInt: {            /* no-push */
  i64 v;
  assert( pTos>=p->aStack );
  applyAffinity(pTos, SQLITE_AFF_NUMERIC, ENC(db));
  if( (pTos->flags & (MEM_Int|MEM_Real))==0 ){
    Release(pTos);
    pTos--;
    pc = pOp->p2 - 1;
    break;
  }
  if( pTos->flags & MEM_Int ){

**
** If the top of the stack is not an integer and P2 is not zero and
** P1 is 1, then the stack is popped.  In all other cases, the depth
** of the stack is unchanged.
*/
case OP_MustBeInt: {            /* no-push */
  assert( pTos>=p->aStack );
  applyAffinity(pTos, SQLITE_AFF_NUMERIC, ENC(db));
  if( (pTos->flags & MEM_Int)==0 ){
    if( pOp->p2==0 ){
      rc = SQLITE_MISMATCH;
      goto abort_due_to_error;
    }else{
      if( pOp->p1 ) popStack(&pTos, 1);
      pc = pOp->p2 - 1;

** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToText: {                  /* same as TK_TO_TEXT, no-push */
  assert( pTos>=p->aStack );
  if( pTos->flags & MEM_Null ) break;
  assert( MEM_Str==(MEM_Blob>>3) );
  pTos->flags |= (pTos->flags&MEM_Blob)>>3;
  applyAffinity(pTos, SQLITE_AFF_TEXT, ENC(db));
  assert( pTos->flags & MEM_Str );
  pTos->flags &= ~(MEM_Int|MEM_Real|MEM_Blob);
  break;
}

/* Opcode: ToBlob * * *
**
** Force the value on the top of the stack to be a BLOB.
** If the value is numeric, convert it to a string first.
** Strings are simply reinterpreted as blobs with no change
** to the underlying data.
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_ToBlob: {                  /* same as TK_TO_BLOB, no-push */
  assert( pTos>=p->aStack );
  if( pTos->flags & MEM_Null ) break;
  if( (pTos->flags & MEM_Blob)==0 ){
    applyAffinity(pTos, SQLITE_AFF_TEXT, ENC(db));
    assert( pTos->flags & MEM_Str );
    pTos->flags |= MEM_Blob;
  }
  pTos->flags &= ~(MEM_Int|MEM_Real|MEM_Str);
  break;
}

      }
      break;
    }
  }

  affinity = pOp->p1 & 0xFF;
  if( affinity ){
    applyAffinity(pNos, affinity, ENC(db));
    applyAffinity(pTos, affinity, ENC(db));
  }

  assert( pOp->p3type==P3_COLLSEQ || pOp->p3==0 );
  res = sqlite3MemCompare(pNos, pTos, (CollSeq*)pOp->p3);
  switch( pOp->opcode ){
    case OP_Eq:    res = res==0;     break;
    case OP_Ne:    res = res!=0;     break;

      rc = sqlite3VdbeMemFromBtree(pCrsr, aOffset[p2], len, pC->isIndex,&sMem);
      if( rc!=SQLITE_OK ){
        goto op_column_out;
      }
      zData = sMem.z;
    }
    sqlite3VdbeSerialGet((u8*)zData, aType[p2], pTos);
    pTos->enc = ENC(db);
  }else{
    if( pOp->p3type==P3_MEM ){
      sqlite3VdbeMemShallowCopy(pTos, (Mem *)(pOp->p3), MEM_Static);
    }else{
      pTos->flags = MEM_Null;
    }
  }

  file_format = p->minWriteFileFormat;

  /* Loop through the elements that will make up the record to figure
  ** out how much space is required for the new record.
  */
  for(pRec=pData0; pRec<=pTos; pRec++){
    if( zAffinity ){
      applyAffinity(pRec, zAffinity[pRec-pData0], ENC(db));
    }
    if( pRec->flags&MEM_Null ){
      containsNull = 1;
    }
    serial_type = sqlite3VdbeSerialType(pRec, file_format);
    nData += sqlite3VdbeSerialTypeLen(serial_type);
    nHdr += sqlite3VarintLen(serial_type);

  ** opened is of type INTKEY, the comparision function will be ignored. */
  rc = sqlite3BtreeCursor(pX, p2, wrFlag,
           sqlite3VdbeRecordCompare, pOp->p3,
           &pCur->pCursor);
  if( pOp->p3type==P3_KEYINFO ){
    pCur->pKeyInfo = (KeyInfo*)pOp->p3;
    pCur->pIncrKey = &pCur->pKeyInfo->incrKey;
    pCur->pKeyInfo->enc = ENC(p->db);
  }else{
    pCur->pKeyInfo = 0;
    pCur->pIncrKey = &pCur->bogusIncrKey;
  }
  switch( rc ){
    case SQLITE_BUSY: {
      p->pc = pc;

      assert( pOp->p3type==P3_KEYINFO );
      rc = sqlite3BtreeCreateTable(pCx->pBt, &pgno, BTREE_ZERODATA); 
      if( rc==SQLITE_OK ){
        assert( pgno==MASTER_ROOT+1 );
        rc = sqlite3BtreeCursor(pCx->pBt, pgno, 1, sqlite3VdbeRecordCompare,
            pOp->p3, &pCx->pCursor);
        pCx->pKeyInfo = (KeyInfo*)pOp->p3;
        pCx->pKeyInfo->enc = ENC(p->db);
        pCx->pIncrKey = &pCx->pKeyInfo->incrKey;
      }
      pCx->isTable = 0;
    }else{
      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, 0, &pCx->pCursor);
      pCx->isTable = 1;
      pCx->pIncrKey = &pCx->bogusIncrKey;

      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
      pC->lastRowid = pTos->i;
      pC->rowidIsValid = res==0;
    }else{
      assert( pTos->flags & MEM_Blob );
      /* Stringify(pTos, ENC(db)); */
      rc = sqlite3BtreeMoveto(pC->pCursor, pTos->z, pTos->n, &res);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
      pC->rowidIsValid = 0;
    }
    pC->deferredMoveto = 0;

  Cursor *pC;
  assert( pTos>=p->aStack );
  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  if( (pC = p->apCsr[i])->pCursor!=0 ){
    int res, rx;
    assert( pC->isTable==0 );
    Stringify(pTos, ENC(db));
    rx = sqlite3BtreeMoveto(pC->pCursor, pTos->z, pTos->n, &res);
    alreadyExists = rx==SQLITE_OK && res==0;
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;
  }
  if( pOp->opcode==OP_Found ){
    if( alreadyExists ) pc = pOp->p2 - 1;

    char *zKey;    /* The value of K */
    int nKey;      /* Number of bytes in K */
    int len;       /* Number of bytes in K without the rowid at the end */
    int szRowid;   /* Size of the rowid column at the end of zKey */

    /* Make sure K is a string and make zKey point to K
    */
    Stringify(pNos, ENC(db));
    zKey = pNos->z;
    nKey = pNos->n;

    szRowid = sqlite3VdbeIdxRowidLen(nKey, (u8*)zKey);
    len = nKey-szRowid;

    /* Search for an entry in P1 where all but the last four bytes match K.

  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  assert( pTos>=p->aStack );
  if( (pC = p->apCsr[i])->pCursor!=0 ){
    int res, rc;
 
    assert( pTos->flags & MEM_Blob );  /* Created using OP_Make*Key */
    Stringify(pTos, ENC(db));
    assert( pC->deferredMoveto==0 );
    *pC->pIncrKey = pOp->p3!=0;
    assert( pOp->p3==0 || pOp->opcode!=OP_IdxGT );
    rc = sqlite3VdbeIdxKeyCompare(pC, pTos->n, (u8*)pTos->z, &res);
    *pC->pIncrKey = 0;
    if( rc!=SQLITE_OK ){
      break;

  }else{
    pTos->z = z;
    pTos->n = strlen(z);
    pTos->flags = MEM_Str | MEM_Dyn | MEM_Term;
    pTos->xDel = 0;
  }
  pTos->enc = SQLITE_UTF8;
  sqlite3VdbeChangeEncoding(pTos, ENC(db));
  sqliteFree(aRoot);
  break;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/* Opcode: FifoWrite * * *
**

  assert( n>=0 );
  pRec = &pTos[1-n];
  assert( pRec>=p->aStack );
  apVal = p->apArg;
  assert( apVal || n==0 );
  for(i=0; i<n; i++, pRec++){
    apVal[i] = pRec;
    storeTypeInfo(pRec, ENC(db));
  }
  ctx.pFunc = (FuncDef*)pOp->p3;
  assert( pOp->p1>=0 && pOp->p1<p->nMem );
  ctx.pMem = pMem = &p->aMem[pOp->p1];
  pMem->n++;
  ctx.isError = 0;
  ctx.pColl = 0;

    ** of the program.  It is only here for testing and debugging.
    ** On the other hand, it does burn CPU cycles every time through
    ** the evaluator loop.  So we can leave it out when NDEBUG is defined.
    */
#ifndef NDEBUG
    /* Sanity checking on the top element of the stack */
    if( pTos>=p->aStack ){
      sqlite3VdbeMemSanity(pTos, ENC(db));
    }
    assert( pc>=-1 && pc<p->nOp );
#ifdef SQLITE_DEBUG
    /* Code for tracing the vdbe stack. */
    if( p->trace && pTos>=p->aStack ){
      int i;
      fprintf(p->trace, "Stack:");

  }
  pVar = &p->aVar[i-1];
  rc = sqlite3VdbeMemSetStr(pVar, zData, nData, encoding, xDel);
  if( rc ){
    return rc;
  }
  if( rc==SQLITE_OK && encoding!=0 ){
    rc = sqlite3VdbeChangeEncoding(pVar, ENC(p->db));
  }
  return rc;
}


/*
** Bind a blob value to an SQL statement variable.

#
#    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 runs all tests.
#
# $Id: quick.test,v 1.40 2006/01/09 16:12:05 danielk1977 Exp $

proc lshift {lvar} {
  upvar $lvar l
  set ret [lindex $l 0]
  set l [lrange $l 1 end]
  return $ret
}

  malloc.test
  malloc2.test
  malloc3.test
  malloc4.test
  memleak.test
  misuse.test
  quick.test

  attachmalloc.test
  utf16.test
  autovacuum_crash.test
  btree8.test
}

if {[sqlite3 -has-codec]} {
  # lappend EXCLUDE \

# 2005 December 30
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    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.
#
#***********************************************************************


#
# $Id: shared.test,v 1.8 2006/01/09 16:12:05 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl
db close

ifcapable !shared_cache {
  finish_test

#             write-transaction, including a simple test to ensure the 
#             external locking protocol is still working.
# shared-3.*: Simple test of read-uncommitted mode.
# shared-4.*: Check that the schema is locked and unlocked correctly.
# shared-5.*: Test that creating/dropping schema items works when databases
#             are attached in different orders to different handles.
# shared-6.*: Locking, UNION ALL queries and sub-queries.
# shared-7.*: Autovacuum and shared-cache.
#

do_test shared-1.1 {
  # Open a second database on the file test.db. It should use the same pager
  # cache and schema as the original connection. Verify that only 1 file is 
  # opened.
  sqlite3 db2 test.db

#--------------------------------------------------------------------------
# Tests shared-7.* test auto-vacuum does not invalidate cursors from
# other shared-cache users when it reorganizes the database on 
# COMMIT.
#
do_test shared-7.1 {
  # This test case sets up a test database in auto-vacuum mode consisting 
  # of two tables, t1 and t2. Both have a single index. Table t1 is 
  # populated first (so consists of pages toward the start of the db file), 
  # t2 second (pages toward the end of the file). 
  sqlite3 db test.db
  sqlite3 db2 test.db
  execsql {
    PRAGMA auto_vacuum = 1;
    BEGIN;
    CREATE TABLE t1(a PRIMARY KEY, b);
    CREATE TABLE t2(a PRIMARY KEY, b);

    COMMIT;
  }
  execsql {
    PRAGMA auto_vacuum;
  }
} {1}
do_test shared-7.2 {
  # This test case deletes the contents of table t1 (the one at the start of
  # the file) while many cursors are open on table t2 and it's index. All of
  # the non-root pages will be moved from the end to the start of the file
  # when the DELETE is committed - this test verifies that moving the pages
  # does not disturb the open cursors.
  #

  proc lockrow {db tbl oids body} {
    set ret [list]
    db eval "SELECT oid AS i, a, b FROM $tbl ORDER BY a" {
      if {$i==[lindex $oids 0]} {
        set noids [lrange $oids 1 end]
        if {[llength $noids]==0} {
          set subret [eval $body]

  set scans [locktblrows db t2 {
    execsql {
      DELETE FROM t1;
    } db2
  }]
  set error 0

  # Test that each SELECT query returned the expected contents of t2.
  foreach s $scans {
    if {[lsort -integer -index 0 $s]!=$::contents} {
      set error 1
    }
  }
  set error
} {0}

catch {db close}
catch {db2 close}

#--------------------------------------------------------------------------
# The following tests try to trick the shared-cache code into assuming
# the wrong encoding for a database.
#
file delete -force test.db test.db-journal
do_test shared-8.1.1 {
  sqlite3 db test.db
  execsql {
    PRAGMA encoding = 'UTF-16';
    SELECT * FROM sqlite_master;
  }
} {}
do_test shared-8.1.2 {
  string range [execsql {PRAGMA encoding;}] 0 end-2
} {UTF-16}
do_test shared-8.1.3 {
  sqlite3 db2 test.db
  execsql {
    PRAGMA encoding = 'UTF-8';
    CREATE TABLE abc(a, b, c);
  } db2
} {}
do_test shared-8.1.4 {
  execsql {
    SELECT * FROM sqlite_master;
  }
} "table abc abc [expr $AUTOVACUUM?3:2] {CREATE TABLE abc(a, b, c)}"
do_test shared-8.1.5 {
  db2 close
  execsql {
    PRAGMA encoding;
  }
} {UTF-8}
file delete -force test2.db test2.db-journal
do_test shared-8.2.1 {
  execsql {
    ATTACH 'test2.db' AS aux;
    SELECT * FROM aux.sqlite_master;
  }
} {}
do_test shared-8.2.2 {
  sqlite3 db2 test2.db
  execsql {
    PRAGMA encoding = 'UTF-16';
    CREATE TABLE def(d, e, f);
  } db2
  string range [execsql {PRAGMA encoding;} db2] 0 end-2
} {UTF-16}
do_test shared-8.2.3 {
  catchsql {
    SELECT * FROM aux.sqlite_master;
  }
} {1 {attached databases must use the same text encoding as main database}}

catch {db close}
catch {db2 close}

finish_test
sqlite3_enable_shared_cache $::enable_shared_cache

mode (disabled by default) intended for use in embedded servers. If
shared-cache mode is enabled and a thread establishes multiple connections
to the same database, the connections share a single data and schema cache.
This can significantly reduce the quantity of memory and IO required by
the system.</p>

<p>Using shared-cache mode imposes some extra restrictions on 
passing database handles between threads and changes the semantics
of the locking model in some cases. These details are described in full by
this document. A basic understanding of the normal SQLite locking model (see
<a href="lockingv3.html">File Locking And Concurrency In SQLite Version 3</a>
for details) is assumed.</p>

}

HEADING 1 {Shared-Cache Locking Model}

puts {
<p>Externally, from the point of view of another process or thread, two
or more database connections using a shared-cache appear as a single 

<i>sqlite_master</i>.
</li>
<li>A connection may not compile an SQL statement if any other connection
is holding a write-lock on the <i>sqlite_master</i> table of any attached
database (including the default database, "main"). 
</li>
</ul>



















}

HEADING 1 {Thread Related Issues}

puts {
<p>When shared-cache mode is enabled, a database connection may only be
used by the thread that called sqlite3_open() to create it. If another