SQLite

  Index *pIdx;                 /* An index to being analyzed */
  int iIdxCur;                 /* Cursor open on index being analyzed */
  Vdbe *v;                     /* The virtual machine being built up */
  int i;                       /* Loop counter */
  int topOfLoop;               /* The top of the loop */
  int endOfLoop;               /* The end of the loop */
  int addr;                    /* The address of an instruction */
  int jZeroRows = 0;           /* 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 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->pSelect ){
    /* Do not gather statistics on views */
    return;
  }
  if( memcmp(pTab->zName, "sqlite_", 7)==0 ){
    /* Do not gather statistics on system tables */
    return;
  }
  assert( sqlite3BtreeHoldsAllMutexes(db) );
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  assert( iDb>=0 );
#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
      db->aDb[iDb].zName ) ){
    return;
  }
#endif

  /* Establish a read-lock on the table at the shared-cache level. */
  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 = pIdx->nColumn;
    KeyInfo *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.  */

    **
    **        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);
  }else{
    assert( jZeroRows>0 );
    addr = sqlite3VdbeAddOp0(v, OP_Goto);
    sqlite3VdbeJumpHere(v, jZeroRows);
  }
  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;
  if( jZeroRows ){
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
** 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);
  if( v ){
    sqlite3VdbeAddOp1(v, OP_LoadAnalysis, iDb);
  }
}

  const char *zDatabase;
};

/*
** This callback is invoked once for each index when reading the
** sqlite_stat1 table.  
**
**     argv[0] = name of the table
**     argv[1] = name of the index (might be NULL)
**     argv[2] = results of analysis - on integer for each column
**
** Entries for which argv[1]==NULL simply record the number of rows in
** 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;
  }
  pTable = sqlite3FindTable(pInfo->db, argv[0], pInfo->zDatabase);
  if( pTable==0 ){
    return 0;
  }
  if( argv[1] ){
    pIndex = sqlite3FindIndex(pInfo->db, argv[1], pInfo->zDatabase);
  }else{
    pIndex = 0;
  }
  n = pIndex ? pIndex->nColumn : 0;
  z = argv[2];
  for(i=0; *z && i<=n; i++){
    v = 0;
    while( (c=z[0])>='0' && c<='9' ){
      v = v*10 + c - '0';
      z++;
    }
    if( i==0 ) pTable->nRowEst = v;
    if( pIndex==0 ) break;
    pIndex->aiRowEst[i] = v;
    if( *z==' ' ) z++;
  }
  return 0;
}

/*

  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);
  }

    pParse->nErr++;
    goto begin_table_error;
  }
  pTable->zName = zName;
  pTable->iPKey = -1;
  pTable->pSchema = db->aDb[iDb].pSchema;
  pTable->nRef = 1;
  pTable->nRowEst = 1000000;
  assert( pParse->pNewTable==0 );
  pParse->pNewTable = pTable;

  /* If this is the magic sqlite_sequence table used by autoincrement,
  ** then record a pointer to this table in the main database structure
  ** so that INSERT can find the table easily.
  */

** 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.
*/
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--;
  }
  if( pIdx->onError!=OE_None ){
    a[pIdx->nColumn] = 1;
  }
}

/*

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

  if( pSrc->notIndexed ){
    /* The NOT INDEXED clause appears in the SQL. */
    return;
  }

  assert( pParse->nQueryLoop >= (double)1 );
  pTable = pSrc->pTab;
  nTableRow = pTable->nRowEst;
  logN = estLog(nTableRow);
  costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1);
  if( costTempIdx>=pCost->rCost ){
    /* The cost of creating the transient table would be greater than
    ** doing the full table scan */
    return;
  }

    /* There is no INDEXED BY clause.  Create a fake Index object to
    ** represent the primary key */
    Index *pFirst;                /* Any other index on the table */
    memset(&sPk, 0, sizeof(Index));
    sPk.nColumn = 1;
    sPk.aiColumn = &aiColumnPk;
    sPk.aiRowEst = aiRowEstPk;

    sPk.onError = OE_Replace;
    sPk.pTable = pSrc->pTab;
    aiRowEstPk[0] = pSrc->pTab->nRowEst;
    aiRowEstPk[1] = 1;
    pFirst = pSrc->pTab->pIndex;
    if( pSrc->notIndexed==0 ){
      sPk.pNext = pFirst;
    }










    pProbe = &sPk;
    wsFlagMask = ~(
        WHERE_COLUMN_IN|WHERE_COLUMN_EQ|WHERE_COLUMN_NULL|WHERE_COLUMN_RANGE
    );
    eqTermMask = WO_EQ|WO_IN;
    pIdx = 0;
  }

    **   
    **   CREATE TABLE t1(a, b); 
    **   CREATE TABLE t2(c, d);
    **   SELECT * FROM t2, t1 WHERE t2.rowid = t1.a;
    **
    ** The best strategy is to iterate through table t1 first. However it
    ** is not possible to determine this with a simple greedy algorithm.
    ** Since the cost of a linear scan through table t2 is the same 
    ** as the cost of a linear scan through table t1, a simple greedy 
    ** algorithm may choose to use t2 for the outer loop, which is a much
    ** costlier approach.
    */
    nUnconstrained = 0;
    notIndexed = 0;
    for(isOptimal=(iFrom<nTabList-1); isOptimal>=0; isOptimal--){

do_test analyze-1.6.3 {
  catchsql {
    CREATE INDEX main.stat1idx ON SQLite_stat1(idx);
  }
} {1 {table sqlite_stat1 may not be indexed}}
do_test analyze-1.7 {
  execsql {
    SELECT * FROM sqlite_stat1 WHERE idx NOT NULL
  }
} {}
do_test analyze-1.8 {
  catchsql {
    ANALYZE main
  }
} {0 {}}
do_test analyze-1.9 {
  execsql {
    SELECT * FROM sqlite_stat1 WHERE idx NOT NULL
  }
} {}
do_test analyze-1.10 {
  catchsql {
    CREATE TABLE t1(a,b);
    ANALYZE main.t1;
  }
} {0 {}}
do_test analyze-1.11 {
  execsql {
    SELECT * FROM sqlite_stat1
  }
} {t1 {} 0}
do_test analyze-1.12 {
  catchsql {
    ANALYZE t1;
  }
} {0 {}}
do_test analyze-1.13 {
  execsql {
    SELECT * FROM sqlite_stat1
  }
} {t1 {} 0}

# Create some indices that can be analyzed.  But do not yet add
# data.  Without data in the tables, no analysis is done.
#
do_test analyze-2.1 {
  execsql {
    CREATE INDEX t1i1 ON t1(a);
    ANALYZE main.t1;
    SELECT * FROM sqlite_stat1 ORDER BY idx;
  }
} {t1 {} 0}
do_test analyze-2.2 {
  execsql {
    CREATE INDEX t1i2 ON t1(b);
    ANALYZE t1;
    SELECT * FROM sqlite_stat1 ORDER BY idx;
  }
} {t1 {} 0}
do_test analyze-2.3 {
  execsql {
    CREATE INDEX t1i3 ON t1(a,b);
    ANALYZE main;
    SELECT * FROM sqlite_stat1 ORDER BY idx;
  }
} {t1 {} 0}

# Start adding data to the table.  Verify that the analysis
# is done correctly.
#
do_test analyze-3.1 {
  execsql {
    INSERT INTO t1 VALUES(1,2);

      CREATE TABLE t4(a,b,c);
      CREATE INDEX t4i1 ON t4(a);
      CREATE INDEX t4i2 ON t4(b,a,c);
      INSERT INTO t4 VALUES(1,2,3);
      ANALYZE;
    }
    set ::authargs
  } {t4 {} main {} t2 {} main {}}
  do_test auth-1.295 {
    execsql {
      SELECT count(*) FROM sqlite_stat1;
    }
  } 3
  proc auth {code args} {
    if {$code=="SQLITE_ANALYZE"} {
      set ::authargs [concat $::authargs $args]
      return SQLITE_DENY
    }
    return SQLITE_OK
  }
  do_test auth-1.296 {
    set ::authargs {}
    catchsql {
      ANALYZE;
    }
  } {1 {not authorized}}
  do_test auth-1.297 {
    execsql {
      SELECT count(*) FROM sqlite_stat1;
    }
  } 3
} ;# ifcapable analyze


# Authorization for ALTER TABLE ADD COLUMN.
# These tests are omitted if the library
# was built without ALTER TABLE support.
ifcapable {altertable} {

      insert into b values ('01',1);
      insert into b values ('01',2);
      insert into b values ('+1',3);
      insert into b values ('+1',4);
      
      select a.*, x.*
        from a, (select key,sum(period) from b group by key) as x
        where a.key=x.key order by 1 desc;
    }
  } {01 data01 01 3 +1 data+1 +1 7}

  # This test case tests the same property as misc4-4.1, but it is
  # a bit smaller which makes it easier to work with while debugging.
  do_test misc4-4.2 {
    execsql {

} ;# ifcapable view

# Ticket #1634
#
do_test select6-9.1 {
  execsql {
    SELECT a.x, b.x FROM t1 AS a, (SELECT x FROM t1 LIMIT 2) AS b
     ORDER BY 1, 2
  }
} {1 1 1 2 2 1 2 2 3 1 3 2 4 1 4 2}
do_test select6-9.2 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT 2);
  }
} {1 2}

  db eval {
     CREATE TABLE t1(x INTEGER, y INTEGER, z TEXT);
     CREATE INDEX t1i1 ON t1(y,z);
     INSERT INTO t1 VALUES(1,2,'three');
     CREATE TABLE t2(a INTEGER, b TEXT);
     INSERT INTO t2 VALUES(2, 'two');
     ANALYZE;
     SELECT * FROM sqlite_stat1 ORDER BY 1, 2;
  }
} {t1 t1i1 {1 1 1} t2 {} 1}

# Modify statistics in order to make the optimizer then that:
#
#   (1)  Table T1 has about 250K entries
#   (2)  There are only about 5 distinct values of T1.
#
# Then run a query with "t1.y IN (SELECT ..)" in the WHERE clause.