SQLite

** information.
*/
typedef struct StatAccum StatAccum;
typedef struct StatSample StatSample;
struct StatSample {
  tRowcnt *anEq;                  /* sqlite_stat4.nEq */
  tRowcnt *anDLt;                 /* sqlite_stat4.nDLt */
  tRowcnt *amxEq;                 /* Maximum length run of equal values */
#ifdef SQLITE_ENABLE_STAT4
  tRowcnt *anLt;                  /* sqlite_stat4.nLt */
  union {
    i64 iRowid;                     /* Rowid in main table of the key */
    u8 *aRowid;                     /* Key for WITHOUT ROWID tables */
  } u;
  u32 nRowid;                     /* Sizeof aRowid[] */

  nKeyCol = sqlite3_value_int(argv[1]);
  assert( nKeyCol<=nCol );
  assert( nKeyCol>0 );

  /* Allocate the space required for the StatAccum object */
  n = sizeof(*p) 
    + sizeof(tRowcnt)*nColUp                  /* StatAccum.anEq */
    + sizeof(tRowcnt)*nColUp                  /* StatAccum.amxEq */
    + sizeof(tRowcnt)*nColUp;                 /* StatAccum.anDLt */
#ifdef SQLITE_ENABLE_STAT4
  if( mxSample ){
    n += sizeof(tRowcnt)*nColUp                  /* StatAccum.anLt */
      + sizeof(StatSample)*(nCol+mxSample)       /* StatAccum.aBest[], a[] */
      + sizeof(tRowcnt)*3*nColUp*(nCol+mxSample);
  }

  p->nEst = sqlite3_value_int64(argv[2]);
  p->nRow = 0;
  p->nLimit = sqlite3_value_int64(argv[3]);
  p->nCol = nCol;
  p->nKeyCol = nKeyCol;
  p->nSkipAhead = 0;
  p->current.anDLt = (tRowcnt*)&p[1];
  p->current.amxEq = &p->current.anDLt[nColUp];
  p->current.anEq = &p->current.amxEq[nColUp];

#ifdef SQLITE_ENABLE_STAT4
  p->mxSample = p->nLimit==0 ? mxSample : 0;
  if( mxSample ){
    u8 *pSpace;                     /* Allocated space not yet assigned */
    int i;                          /* Used to iterate through p->aSample[] */

  UNUSED_PARAMETER( argc );
  UNUSED_PARAMETER( context );
  assert( p->nCol>0 );
  assert( iChng<p->nCol );

  if( p->nRow==0 ){
    /* This is the first call to this function. Do initialization. */
    for(i=0; i<p->nCol; i++){
      p->current.anEq[i] = 1;
      p->current.amxEq[i] = 1;
    }
  }else{
    /* Second and subsequent calls get processed here */
#ifdef SQLITE_ENABLE_STAT4
    if( p->mxSample ) samplePushPrevious(p, iChng);
#endif

    /* Update anDLt[], anLt[] and anEq[] to reflect the values that apply
    ** to the current row of the index. */
    for(i=0; i<iChng; i++){
      p->current.anEq[i]++;
    }
    for(i=iChng; i<p->nCol; i++){
      p->current.anDLt[i]++;
#ifdef SQLITE_ENABLE_STAT4
      if( p->mxSample ) p->current.anLt[i] += p->current.anEq[i];
#endif
      if( p->current.amxEq[i]<p->current.anEq[i] ){
        p->current.amxEq[i] = p->current.anEq[i];
      }
      p->current.anEq[i] = 1;
    }
  }

  p->nRow++;
#ifdef SQLITE_ENABLE_STAT4
  if( p->mxSample ){

    ** the index. The first integer in the list is the total number of 
    ** entries in the index. There is one additional integer in the list 
    ** for each indexed column. This additional integer is an estimate of
    ** the number of rows matched by a equality query on the index using
    ** a key with the corresponding number of fields. In other words,
    ** if the index is on columns (a,b) and the sqlite_stat1 value is 
    ** "100 10 2", then SQLite estimates that:
    **   |   | |
    **   |   | `--  "WHERE a=? AND b=?" matches approximately 2 rows
    **   |   `----  "WHERE a=?" matches approximately 10 rows
    **   `--------  There are approximately 100 rows in the index total
    **
    ** If D is the count of distinct values and K is the total number of 
    ** rows, then each estimate is usually computed as:
    **
    **        I = (K+D-1)/D
    **
    ** Adjustments to the I value are made in some cases.  See comments


    ** in-line below.
    */
    sqlite3_str sStat;   /* Text of the constructed "stat" line */
    int i;               /* Loop counter */
    int bUneven = 0;     /* True if the uneven=... argument is needed */
    u64 nRow;            /* Number of rows in the index */

    sqlite3StrAccumInit(&sStat, 0, 0, 0, (p->nKeyCol+1)*100);
    nRow =  p->nSkipAhead ? p->nEst : p->nRow;
    sqlite3_str_appendf(&sStat, "%llu", nRow);

    for(i=0; i<p->nKeyCol; i++){
      u64 nDistinct = p->current.anDLt[i] + 1;
      u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
      u64 mx = p->current.amxEq[i];
      if( nDistinct==1 && p->nLimit>0 ){
        /* If we never saw more than a single value in a PRAGMA analysis_limit
        ** search, then set the estimated number of matching rows to the
        ** estimated number of rows in the index. */
        iVal = p->nEst;
      }else if( iVal<mx/10 ){
        /*              ^^-- TUNING: threshold for when var=... is reported.
        ** tag-20231231-01:  Report var=... if the maximum run of identical
        ** values ever reaches or exceeds 10 (or so) times the average run
        ** for any column of the index.
        **
        ** The reporting threshold of 10 is tunable, but if changed, one
        ** should also consider changing the aiRowLogEst adjustment factor at
        ** tag-20231231-02.
        */
        bUneven = 1;
      }else if( iVal==2 && p->nRow*10 <= nDistinct*11 ){
        /* If the value is less than or equal to 1.1, round it down to 1.0 */
        iVal = 1;
      }
      sqlite3_str_appendf(&sStat, " %llu", iVal);
      assert( p->current.anEq[i] );

    }
    if( bUneven ){
      char cSep = '=';
      sqlite3_str_appendf(&sStat, " var");
      for(i=0; i<p->nKeyCol; i++){
        u64 nDistinct = p->current.anDLt[i] + 1;
        u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
        u64 mx = p->current.amxEq[i];
        int iRatio = mx/iVal;
        sqlite3_str_appendf(&sStat, "%c%d", cSep, iRatio);
        cSep = ',';
      }
    }
    sqlite3ResultStrAccum(context, &sStat);
  }
#ifdef SQLITE_ENABLE_STAT4
  else if( eCall==STAT_GET_ROWID ){
    if( p->iGet<0 ){
      samplePushPrevious(p, 0);

  tRowcnt v;

#ifdef SQLITE_ENABLE_STAT4
  if( z==0 ) z = "";
#else
  assert( z!=0 );
#endif
  for(i=0; i<nOut; i++){
    v = 0;
    while( (c=z[0])>='0' && c<='9' ){
      v = v*10 + c - '0';
      z++;
    }
#ifdef SQLITE_ENABLE_STAT4
    if( aOut ) aOut[i] = v;

#ifndef SQLITE_ENABLE_STAT4
  assert( pIndex!=0 ); {
#else
  if( pIndex ){
#endif
    pIndex->bUnordered = 0;
    pIndex->noSkipScan = 0;
    pIndex->bSlow = 0;
    assert( aLog!=0 );
    while( z[0] ){
      if( sqlite3_strglob("unordered*", z)==0 ){
        pIndex->bUnordered = 1;
      }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){
        int sz = sqlite3Atoi(z+3);
        if( sz<2 ) sz = 2;
        pIndex->szIdxRow = sqlite3LogEst(sz);
      }else if( sqlite3_strglob("noskipscan*", z)==0 ){
        pIndex->noSkipScan = 1;
      }else if( sqlite3_strglob("var=[0-9]*", z)==0 ){
        /* An argument like "var=N1,N2,...NN" means that the maximum length
        ** run of the same value is Nx times longer than the average for
        ** the X-th column of the index.
        **
        ** For this implementation, go through the iaRowLogEst[] array and
        ** increase each value by 1/10th of the average value, to account
        ** for the variability of the estimate.
        **
        ** tag-20231231-02:  The 1/10th value is tunable.  See the tuning
        ** comment in the body of the loop.  The ANALYZE command only
        ** inserts a var=... argument if one or more of the Nx values is
        ** within the tuning range, so if changing the tuning factor here,
        ** consider also changing it at tag-20232131-01.
        **
        ** The stat column continue to hold the average run length for the
        ** initial integers, for backwards compatibility.
        */
        int jj = 1;
        int kk = 4;
        LogEst mx = aLog[0];
        for(jj=1; sqlite3Isdigit(z[kk]) && jj<nOut; jj++){
          u64 vx = z[kk++] - '0';
          LogEst scale;
          while( sqlite3Isdigit(z[kk]) ){ vx = vx*10 + z[kk++]-'0'; }
          scale = sqlite3LogEst(vx);
          if( scale>33 ){
                /*  ^^----- TUNING --------------vv    See tag 20231231-02 */
            LogEst adjusted = aLog[jj] + scale - 33;
            if( adjusted>mx ) adjusted = mx;
            aLog[jj] = adjusted;
          }
          if( z[kk]==',' ) kk++;
        }
      }
#ifdef SQLITE_ENABLE_COSTMULT
      else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){
        pIndex->pTable->costMult = sqlite3LogEst(sqlite3Atoi(z+9));
      }
#endif
      while( z[0]!=0 && z[0]!=' ' ) z++;
      while( z[0]==' ' ) z++;
    }

    /* Set the bSlow flag if the peak number of rows obtained
    ** from a full equality match is so large that a full table scan
    ** seems likely to be faster than using the index.
    */
    if( aLog[0] > 66                       /* Index has more than 100 rows */
     && aLog[0] <= aLog[pIndex->nKeyCol]   /* And only a single value seen */
    ){
      pIndex->bSlow = 1;
    }
  }
}

/*
** This callback is invoked once for each index when reading the
** sqlite_stat1 table.  
**

    pIndex->hasStat1 = 1;
    if( pIndex->pPartIdxWhere==0 ){
      pTable->nRowLogEst = pIndex->aiRowLogEst[0];
      pTable->tabFlags |= TF_HasStat1;
    }
  }else{
    Index fakeIdx;
    memset(&fakeIdx, 0, sizeof(fakeIdx));
    fakeIdx.szIdxRow = pTable->szTabRow;
#ifdef SQLITE_ENABLE_COSTMULT
    fakeIdx.pTable = pTable;
#endif
    decodeIntArray((char*)z, 1, 0, &pTable->nRowLogEst, &fakeIdx);
    pTable->szTabRow = fakeIdx.szIdxRow;
    pTable->tabFlags |= TF_HasStat1;

        );
      }
    }
  }
  break;

#ifdef SQLITE_DEBUG
  /* The output of this pragma is undocumented in the official documentation
  ** because it is subject to change, and we don't want people coming to
  ** rely on it.
  **
  ** Columns:
  **    tbl              Name of a table that is being described
  **    idx              Name of an index (belonging to tbl) being described
  **    wdth             LogEst of the on-disk estimated bytes per row
  **    hght             LogEst of the estimated number of rows
  **    flgs             tabFlags for tables
  **    est              aiRowLogEst[] values for indexes + "slow" flag
  */
  case PragTyp_STATS: {
    Index *pIdx;
    HashElem *i;
    sqlite3_str est;
    sqlite3StrAccumInit(&est, 0, 0, 0, SQLITE_MAX_LENGTH);
    pParse->nMem = 6;
    sqlite3CodeVerifySchema(pParse, iDb);
    for(i=sqliteHashFirst(&pDb->pSchema->tblHash); i; i=sqliteHashNext(i)){
      Table *pTab = sqliteHashData(i);
      sqlite3VdbeMultiLoad(v, 1, "ssiiis",
           sqlite3PreferredTableName(pTab->zName),
           0,
           pTab->szTabRow,
           pTab->nRowLogEst,
           pTab->tabFlags,
           0);
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        int j;
        est.nChar = 0;
        for(j=1; j<pIdx->nKeyCol+1; j++){
          if( j>1 ) sqlite3_str_append(&est, " ", 1);
          sqlite3_str_appendf(&est, "%d", pIdx->aiRowLogEst[j]);
        }
        if( pIdx->bSlow ) sqlite3_str_append(&est, " slow", 5);
        sqlite3VdbeMultiLoad(v, 2, "siiisX",
           pIdx->zName,
           pIdx->szIdxRow,
           pIdx->aiRowLogEst[0],
           pIdx->hasStat1,
           sqlite3_str_value(&est));
        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 6);
        sqlite3_str_reset(&est);
      }
    }
  }
  break;
#endif

  case PragTyp_INDEX_INFO: if( zRight ){

                           /* table_info reuses 8 */
  /*  15 */ "schema",      /* Used by: table_list */
  /*  16 */ "name",       
  /*  17 */ "type",       
  /*  18 */ "ncol",       
  /*  19 */ "wr",         
  /*  20 */ "strict",     
  /*  21 */ "tbl",         /* Used by: stats */
  /*  22 */ "idx",        
  /*  23 */ "wdth",       
  /*  24 */ "hght",       
  /*  25 */ "flgs",       
  /*  26 */ "est",        
  /*  27 */ "seqno",       /* Used by: index_xinfo */
  /*  28 */ "cid",        
  /*  29 */ "name",       
  /*  30 */ "desc",       
  /*  31 */ "coll",       
  /*  32 */ "key",        
  /*  33 */ "name",        /* Used by: function_list */
  /*  34 */ "builtin",    
  /*  35 */ "type",       
  /*  36 */ "enc",        
  /*  37 */ "narg",       
  /*  38 */ "flags",      
  /*  39 */ "seq",         /* Used by: index_list */
  /*  40 */ "name",       
  /*  41 */ "unique",     
  /*  42 */ "origin",     
  /*  43 */ "partial",    
  /*  44 */ "table",       /* Used by: foreign_key_check */
  /*  45 */ "rowid",      
  /*  46 */ "parent",     
  /*  47 */ "fkid",       
                           /* index_info reuses 27 */
  /*  48 */ "seq",         /* Used by: database_list */

  /*  49 */ "name",       
  /*  50 */ "file",       
  /*  51 */ "busy",        /* Used by: wal_checkpoint */
  /*  52 */ "log",        
  /*  53 */ "checkpointed",
                           /* collation_list reuses 39 */
  /*  54 */ "database",    /* Used by: lock_status */
  /*  55 */ "status",     
  /*  56 */ "cache_size",  /* Used by: default_cache_size */
                           /* module_list pragma_list reuses 9 */
  /*  57 */ "timeout",     /* Used by: busy_timeout */
};

/* Definitions of all built-in pragmas */
typedef struct PragmaName {
  const char *const zName; /* Name of pragma */
  u8 ePragTyp;             /* PragTyp_XXX value */
  u8 mPragFlg;             /* Zero or more PragFlg_XXX values */

  /* ColNames:  */ 0, 0,
  /* iArg:      */ SQLITE_AutoIndex },
#endif
#endif
 {/* zName:     */ "busy_timeout",
  /* ePragTyp:  */ PragTyp_BUSY_TIMEOUT,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 57, 1,
  /* iArg:      */ 0 },
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "cache_size",
  /* ePragTyp:  */ PragTyp_CACHE_SIZE,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },

  /* ColNames:  */ 0, 0,
  /* iArg:      */ SQLITE_CkptFullFSync },
#endif
#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
 {/* zName:     */ "collation_list",
  /* ePragTyp:  */ PragTyp_COLLATION_LIST,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 39, 2,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_COMPILEOPTION_DIAGS)
 {/* zName:     */ "compile_options",
  /* ePragTyp:  */ PragTyp_COMPILE_OPTIONS,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 0, 0,

  /* ColNames:  */ 0, 0,
  /* iArg:      */ BTREE_DATA_VERSION },
#endif
#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
 {/* zName:     */ "database_list",
  /* ePragTyp:  */ PragTyp_DATABASE_LIST,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 48, 3,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && !defined(SQLITE_OMIT_DEPRECATED)
 {/* zName:     */ "default_cache_size",
  /* ePragTyp:  */ PragTyp_DEFAULT_CACHE_SIZE,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
  /* ColNames:  */ 56, 1,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
 {/* zName:     */ "defer_foreign_keys",
  /* ePragTyp:  */ PragTyp_FLAG,
  /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,

  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
 {/* zName:     */ "foreign_key_check",
  /* ePragTyp:  */ PragTyp_FOREIGN_KEY_CHECK,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 44, 4,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FOREIGN_KEY)
 {/* zName:     */ "foreign_key_list",
  /* ePragTyp:  */ PragTyp_FOREIGN_KEY_LIST,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 0, 8,

  /* iArg:      */ SQLITE_FullFSync },
#endif
#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
#if !defined(SQLITE_OMIT_INTROSPECTION_PRAGMAS)
 {/* zName:     */ "function_list",
  /* ePragTyp:  */ PragTyp_FUNCTION_LIST,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 33, 6,
  /* iArg:      */ 0 },
#endif
#endif
 {/* zName:     */ "hard_heap_limit",
  /* ePragTyp:  */ PragTyp_HARD_HEAP_LIMIT,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 0, 0,

  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
 {/* zName:     */ "index_info",
  /* ePragTyp:  */ PragTyp_INDEX_INFO,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 27, 3,
  /* iArg:      */ 0 },
 {/* zName:     */ "index_list",
  /* ePragTyp:  */ PragTyp_INDEX_LIST,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 39, 5,
  /* iArg:      */ 0 },
 {/* zName:     */ "index_xinfo",
  /* ePragTyp:  */ PragTyp_INDEX_INFO,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 27, 6,
  /* iArg:      */ 1 },
#endif
#if !defined(SQLITE_OMIT_INTEGRITY_CHECK)
 {/* zName:     */ "integrity_check",
  /* ePragTyp:  */ PragTyp_INTEGRITY_CHECK,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 0, 0,

  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
#endif
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
 {/* zName:     */ "lock_status",
  /* ePragTyp:  */ PragTyp_LOCK_STATUS,
  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 54, 2,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "locking_mode",
  /* ePragTyp:  */ PragTyp_LOCKING_MODE,
  /* ePragFlg:  */ PragFlg_Result0|PragFlg_SchemaReq,
  /* ColNames:  */ 0, 0,

  /* iArg:      */ SQLITE_SqlTrace },
#endif
#endif
#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS) && defined(SQLITE_DEBUG)
 {/* zName:     */ "stats",
  /* ePragTyp:  */ PragTyp_STATS,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq,
  /* ColNames:  */ 21, 6,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "synchronous",
  /* ePragTyp:  */ PragTyp_SYNCHRONOUS,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
  /* ColNames:  */ 0, 0,

  /* ePragTyp:  */ PragTyp_WAL_AUTOCHECKPOINT,
  /* ePragFlg:  */ 0,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 {/* zName:     */ "wal_checkpoint",
  /* ePragTyp:  */ PragTyp_WAL_CHECKPOINT,
  /* ePragFlg:  */ PragFlg_NeedSchema,
  /* ColNames:  */ 51, 3,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
 {/* zName:     */ "writable_schema",
  /* ePragTyp:  */ PragTyp_FLAG,
  /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ SQLITE_WriteSchema|SQLITE_NoSchemaError },
#endif
};
/* Number of pragmas: 68 on by default, 78 total. */

  unsigned bUnordered:1;   /* Use this index for == or IN queries only */
  unsigned uniqNotNull:1;  /* True if UNIQUE and NOT NULL for all columns */
  unsigned isResized:1;    /* True if resizeIndexObject() has been called */
  unsigned isCovering:1;   /* True if this is a covering index */
  unsigned noSkipScan:1;   /* Do not try to use skip-scan if true */
  unsigned hasStat1:1;     /* aiRowLogEst values come from sqlite_stat1 */
  unsigned bNoQuery:1;     /* Do not use this index to optimize queries */
  unsigned bSlow:1;        /* This index is not good for equality lookups */
  unsigned bAscKeyBug:1;   /* True if the bba7b69f9849b5bf bug applies */
  unsigned bHasVCol:1;     /* Index references one or more VIRTUAL columns */
  unsigned bHasExpr:1;     /* Index contains an expression, either a literal
                           ** expression, or a reference to a VIRTUAL column */
#ifdef SQLITE_ENABLE_STAT4
  int nSample;             /* Number of elements in aSample[] */
  int mxSample;            /* Number of slots allocated to aSample[] */

  assert( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 );
  if( pNew->wsFlags & WHERE_BTM_LIMIT ){
    opMask = WO_LT|WO_LE;
  }else{
    assert( pNew->u.btree.nBtm==0 );
    opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE|WO_ISNULL|WO_IS;
  }
  if( pProbe->bUnordered || pProbe->bSlow ){
    if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE);
    if( pProbe->bSlow )      opMask &= ~(WO_EQ|WO_IN|WO_IS);
  }

  assert( pNew->u.btree.nEq<pProbe->nColumn );
  assert( pNew->u.btree.nEq<pProbe->nKeyCol
       || pProbe->idxType!=SQLITE_IDXTYPE_PRIMARYKEY );

  saved_nEq = pNew->u.btree.nEq;
  saved_nBtm = pNew->u.btree.nBtm;

  TYPE: TABLE_LIST
  FLAG: NeedSchema Result1
  COLS: schema name type ncol wr strict
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)

  NAME: stats
  FLAG: NeedSchema Result0 SchemaReq
  COLS: tbl idx wdth hght flgs est
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS) && defined(SQLITE_DEBUG)

  NAME: index_info
  TYPE: INDEX_INFO
  ARG:  0
  FLAG: NeedSchema Result1 SchemaOpt
  COLS: seqno cid name