** 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 for sqlite_stat3:
**
** The sqlite_stat3 table may contain 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 entries 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
................................................................................
      aRoot[i] = pPK->tnum;
      assert( aRoot[i]>0 );
      if( zWhere ){
        sqlite4NestedParse(pParse,
           "DELETE FROM %Q.%s WHERE %s=%Q", pDb->zName, zTab, zWhereType, zWhere
        );
      }else{
        /* The sqlite_stat[12] table already exists.  Delete all rows. */
        sqlite4VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
      }
    }
  }

  /* Open the sqlite_stat[13] tables for writing. */
  for(i=0; i<ArraySize(aTable); i++){
................................................................................
  int mxSample;             /* Maximum number of samples to accumulate */
  int nSample;              /* Current number of samples */
  u32 iPrn;                 /* Pseudo-random number used for sampling */
  struct Stat3Sample {
    void *pKey;                /* Index key for this sample */
    int nKey;                  /* Bytes of pKey in use */
    int nAlloc;                /* Bytes of space allocated at pKey */

    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 SQLITE4_ENABLE_STAT3




static void delStat3Accum(void *pCtx, void *p){
  sqlite4 *db = (sqlite4*)pCtx;






  sqlite4DbFree(db, p);
}

/*
** 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).
................................................................................
  }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];
    memset(pSample, 0, sizeof(struct Stat3Sample));


  }else{
    pSample = &p->a[p->nSample++];
  }

  pKey = sqlite4_value_blob(argv[3], &nKey);
  if( nKey>pSample->nAlloc ){
    sqlite4 *db = sqlite4_context_db_handle(context);
................................................................................
  0,                /* xFinalize */
  "stat3_get",      /* zName */
  0,                /* pHash */
  0                 /* pDestructor */
};
#endif /* SQLITE4_ENABLE_STAT3 */




/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
  Table *pTab,     /* Table whose indices are to be analyzed */
................................................................................
#endif

  iIdxCur = pParse->nTab++;
  sqlite4VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol;
    KeyInfo *pKey;
    int *aChngAddr;              /* Array of jump instruction addresses */
    int regCnt;                  /* Total number of rows in table. */
    int regPrev;                 /* Previous index key read from database */
    int aregCard;                /* Cardinality array registers */
#ifdef SQLITE4_ENABLE_STAT3
    int addrAddimm;              /* Address at top of stat3 output loop */
    int addrIsnull;              /* Another address within the stat3 loop */
#endif

    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
    VdbeNoopComment((v, "Begin analysis of %s", pIdx->zName));
    nCol = pIdx->nColumn;
    aChngAddr = sqlite4DbMallocRaw(db, sizeof(int)*nCol);
    if( aChngAddr==0 ) continue;
    pKey = sqlite4IndexKeyinfo(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==sqlite4SchemaToIndex(db, pIdx->pSchema) );
................................................................................
  sqlite4VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
  sqlite4VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
  sqlite4VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regNewRowid);
  sqlite4VdbeChangeP5(v, OPFLAG_APPEND);
  if( pParse->nMem<regRec ) pParse->nMem = regRec;
  sqlite4VdbeJumpHere(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 = sqlite4GetVdbe(pParse);

** 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 for sqlite_stat3:
**
** The sqlite_stat3 table may contain multiple entries for each index.
** The idx column names the index and the tbl column contains the name
** of the indexed table. If the idx and tbl columns are the same, then the
** sample is of the PRIMARY KEY index. The sample column is a value taken
** from the left-most column of the index encoded using the key-encoding.
** 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 entries 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
................................................................................
      aRoot[i] = pPK->tnum;
      assert( aRoot[i]>0 );
      if( zWhere ){
        sqlite4NestedParse(pParse,
           "DELETE FROM %Q.%s WHERE %s=%Q", pDb->zName, zTab, zWhereType, zWhere
        );
      }else{
        /* The sqlite_stat[13] table already exists.  Delete all rows. */
        sqlite4VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
      }
    }
  }

  /* Open the sqlite_stat[13] tables for writing. */
  for(i=0; i<ArraySize(aTable); i++){
................................................................................
  int mxSample;             /* Maximum number of samples to accumulate */
  int nSample;              /* Current number of samples */
  u32 iPrn;                 /* Pseudo-random number used for sampling */
  struct Stat3Sample {
    void *pKey;                /* Index key for this sample */
    int nKey;                  /* Bytes of pKey in use */
    int nAlloc;                /* Bytes of space allocated at pKey */

    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 value (pseudo-random) */
  } *a;                     /* An array of samples */
};

#ifdef SQLITE4_ENABLE_STAT3

/*
** Delete a Stat3Accum object.
*/
static void delStat3Accum(void *pCtx, void *pDel){
  sqlite4 *db = (sqlite4*)pCtx;
  Stat3Accum *p = (Stat3Accum*)pDel;
  int i;

  for(i=0; i<p->nSample; i++){
    sqlite4DbFree(db, p->a[i].pKey);
  }
  sqlite4DbFree(db, p);
}

/*
** 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).
................................................................................
  }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 ){
    void *pKey = p->a[iMin].pKey;
    int nAlloc = p->a[iMin].nAlloc;
    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];
    memset(pSample, 0, sizeof(struct Stat3Sample));
    pSample->pKey = pKey;
    pSample->nAlloc = nAlloc;
  }else{
    pSample = &p->a[p->nSample++];
  }

  pKey = sqlite4_value_blob(argv[3], &nKey);
  if( nKey>pSample->nAlloc ){
    sqlite4 *db = sqlite4_context_db_handle(context);
................................................................................
  0,                /* xFinalize */
  "stat3_get",      /* zName */
  0,                /* pHash */
  0                 /* pDestructor */
};
#endif /* SQLITE4_ENABLE_STAT3 */




/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
  Table *pTab,     /* Table whose indices are to be analyzed */
................................................................................
#endif

  iIdxCur = pParse->nTab++;
  sqlite4VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol;
    KeyInfo *pKey;

    int regCnt;                  /* Total number of rows in table. */
    int regPrev;                 /* Previous index key read from database */
    int aregCard;                /* Cardinality array registers */
#ifdef SQLITE4_ENABLE_STAT3
    int addrAddimm;              /* Address at top of stat3 output loop */
    int addrIsnull;              /* Another address within the stat3 loop */
#endif

    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
    VdbeNoopComment((v, "Begin analysis of %s", pIdx->zName));
    nCol = pIdx->nColumn;


    pKey = sqlite4IndexKeyinfo(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==sqlite4SchemaToIndex(db, pIdx->pSchema) );
................................................................................
  sqlite4VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
  sqlite4VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
  sqlite4VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regNewRowid);
  sqlite4VdbeChangeP5(v, OPFLAG_APPEND);
  if( pParse->nMem<regRec ) pParse->nMem = regRec;
  sqlite4VdbeJumpHere(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 = sqlite4GetVdbe(pParse);