SQLite

      pIndex->aiRowEst = (tRowcnt*)sqlite3MallocZero(sizeof(tRowcnt) * nCol);
      if( pIndex->aiRowEst==0 ) sqlite3OomFault(pInfo->db);
    }
    aiRowEst = pIndex->aiRowEst;
#endif
    pIndex->bUnordered = 0;
    decodeIntArray((char*)z, nCol, aiRowEst, pIndex->aiRowLogEst, pIndex);
    pIndex->hasStat1 = 1;
    if( pIndex->pPartIdxWhere==0 ){
      pTable->nRowLogEst = pIndex->aiRowLogEst[0];
      pTable->tabFlags |= TF_HasStat1;
    }
  }else{
    Index 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;
  }

  return 0;
}

/*
** If the Index.aSample variable is not NULL, delete the aSample[] array

** code may be ignored.
*/
int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
  analysisInfo sInfo;
  HashElem *i;
  char *zSql;
  int rc = SQLITE_OK;
  Schema *pSchema = db->aDb[iDb].pSchema;

  assert( iDb>=0 && iDb<db->nDb );
  assert( db->aDb[iDb].pBt!=0 );

  /* Clear any prior statistics */
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  for(i=sqliteHashFirst(&pSchema->tblHash); i; i=sqliteHashNext(i)){
    Table *pTab = sqliteHashData(i);
    pTab->tabFlags &= ~TF_HasStat1;
  }
  for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    pIdx->hasStat1 = 0;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    sqlite3DeleteIndexSamples(db, pIdx);
    pIdx->aSample = 0;
#endif
  }

  /* Load new statistics out of the sqlite_stat1 table */

      rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
      sqlite3DbFree(db, zSql);
    }
  }

  /* Set appropriate defaults on all indexes not in the sqlite_stat1 table */
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    if( !pIdx->hasStat1 ) sqlite3DefaultRowEst(pIdx);
  }

  /* Load the statistics from the sqlite_stat4 table. */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  if( rc==SQLITE_OK && OptimizationEnabled(db, SQLITE_Stat34) ){
    db->lookaside.bDisable++;
    rc = loadStat4(db, sInfo.zDatabase);
    db->lookaside.bDisable--;
  }
  for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    sqlite3_free(pIdx->aiRowEst);
    pIdx->aiRowEst = 0;
  }
#endif

  if( rc==SQLITE_NOMEM ){

*/
void sqlite3DefaultRowEst(Index *pIdx){
  /*                10,  9,  8,  7,  6 */
  LogEst aVal[] = { 33, 32, 30, 28, 26 };
  LogEst *a = pIdx->aiRowLogEst;
  int nCopy = MIN(ArraySize(aVal), pIdx->nKeyCol);
  int i;

  /* Indexes with default row estimates should not have stat1 data */
  assert( !pIdx->hasStat1 );

  /* Set the first entry (number of rows in the index) to the estimated 
  ** number of rows in the table, or half the number of rows in the table
  ** for a partial index.   But do not let the estimate drop below 10. */
  a[0] = pIdx->pTable->nRowLogEst;
  if( pIdx->pPartIdxWhere!=0 ) a[0] -= 10;  assert( 10==sqlite3LogEst(2) );
  if( a[0]<33 ) a[0] = 33;                  assert( 33==sqlite3LogEst(10) );

               k);
        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 6);
      }
    }
  }
  break;

#ifdef SQLITE_DEBUG
  case PragTyp_STATS: {
    Index *pIdx;
    HashElem *i;
    pParse->nMem = 5;
    sqlite3CodeVerifySchema(pParse, iDb);
    for(i=sqliteHashFirst(&pDb->pSchema->tblHash); i; i=sqliteHashNext(i)){
      Table *pTab = sqliteHashData(i);
      sqlite3VdbeMultiLoad(v, 1, "ssiii",
           pTab->zName,
           0,
           pTab->szTabRow,
           pTab->nRowLogEst,
           pTab->tabFlags);
      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 5);
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        sqlite3VdbeMultiLoad(v, 2, "siii",
           pIdx->zName,
           pIdx->szIdxRow,
           pIdx->aiRowLogEst[0],
           pIdx->hasStat1);
        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 5);
      }
    }
  }
  break;
#endif

  case PragTyp_INDEX_INFO: if( zRight ){
    Index *pIdx;
    Table *pTab;
    pIdx = sqlite3FindIndex(db, zRight, zDb);
    if( pIdx ){
      int i;

#define PragTyp_LOCKING_MODE                  22
#define PragTyp_PAGE_COUNT                    23
#define PragTyp_MMAP_SIZE                     24
#define PragTyp_PAGE_SIZE                     25
#define PragTyp_SECURE_DELETE                 26
#define PragTyp_SHRINK_MEMORY                 27
#define PragTyp_SOFT_HEAP_LIMIT               28

#define PragTyp_SYNCHRONOUS                   29
#define PragTyp_TABLE_INFO                    30
#define PragTyp_TEMP_STORE                    31
#define PragTyp_TEMP_STORE_DIRECTORY          32
#define PragTyp_THREADS                       33
#define PragTyp_WAL_AUTOCHECKPOINT            34
#define PragTyp_WAL_CHECKPOINT                35
#define PragTyp_ACTIVATE_EXTENSIONS           36
#define PragTyp_HEXKEY                        37
#define PragTyp_KEY                           38
#define PragTyp_REKEY                         39
#define PragTyp_LOCK_STATUS                   40
#define PragTyp_PARSER_TRACE                  41
#define PragTyp_STATS                         42

/* Property flags associated with various pragma. */
#define PragFlg_NeedSchema 0x01 /* Force schema load before running */
#define PragFlg_NoColumns  0x02 /* OP_ResultRow called with zero columns */
#define PragFlg_NoColumns1 0x04 /* zero columns if RHS argument is present */
#define PragFlg_ReadOnly   0x08 /* Read-only HEADER_VALUE */
#define PragFlg_Result0    0x10 /* Acts as query when no argument */

  /*   4 */ "notnull",    
  /*   5 */ "dflt_value", 
  /*   6 */ "pk",         
  /*   7 */ "table",       /* Used by: stats */
  /*   8 */ "index",      
  /*   9 */ "width",      
  /*  10 */ "height",     
  /*  11 */ "flags",      
  /*  12 */ "seqno",       /* Used by: index_info */
  /*  13 */ "cid",        
  /*  14 */ "name",       
  /*  15 */ "seqno",       /* Used by: index_xinfo */
  /*  16 */ "cid",        
  /*  17 */ "name",       
  /*  18 */ "desc",       
  /*  19 */ "coll",       
  /*  20 */ "key",        
  /*  21 */ "seq",         /* Used by: index_list */
  /*  22 */ "name",       
  /*  23 */ "unique",     
  /*  24 */ "origin",     
  /*  25 */ "partial",    
  /*  26 */ "seq",         /* Used by: database_list */
  /*  27 */ "name",       
  /*  28 */ "file",       
  /*  29 */ "seq",         /* Used by: collation_list */
  /*  30 */ "name",       
  /*  31 */ "id",          /* Used by: foreign_key_list */
  /*  32 */ "seq",        
  /*  33 */ "table",      
  /*  34 */ "from",       
  /*  35 */ "to",         
  /*  36 */ "on_update",  
  /*  37 */ "on_delete",  
  /*  38 */ "match",      
  /*  39 */ "table",       /* Used by: foreign_key_check */
  /*  40 */ "rowid",      
  /*  41 */ "parent",     
  /*  42 */ "fkid",       
  /*  43 */ "busy",        /* Used by: wal_checkpoint */
  /*  44 */ "log",        
  /*  45 */ "checkpointed",
  /*  46 */ "timeout",     /* Used by: busy_timeout */
  /*  47 */ "database",    /* Used by: lock_status */
  /*  48 */ "status",     
};

/* 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:  */ 46, 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:  */ 29, 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_NeedSchema|PragFlg_Result0,
  /* ColNames:  */ 26, 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:  */ 0, 1,

  /* 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,
  /* ColNames:  */ 39, 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:  */ 31, 8,
  /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
 {/* zName:     */ "foreign_keys",
  /* ePragTyp:  */ PragTyp_FLAG,
  /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,

  /* 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:  */ 12, 3,
  /* iArg:      */ 0 },
 {/* zName:     */ "index_list",
  /* ePragTyp:  */ PragTyp_INDEX_LIST,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 21, 5,
  /* iArg:      */ 0 },
 {/* zName:     */ "index_xinfo",
  /* ePragTyp:  */ PragTyp_INDEX_INFO,
  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
  /* ColNames:  */ 15, 6,
  /* iArg:      */ 1 },
#endif
#if !defined(SQLITE_OMIT_INTEGRITY_CHECK)
 {/* zName:     */ "integrity_check",
  /* ePragTyp:  */ PragTyp_INTEGRITY_CHECK,
  /* ePragFlg:  */ PragFlg_NeedSchema,
  /* 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:  */ 47, 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,

 {/* zName:     */ "sql_trace",
  /* ePragTyp:  */ PragTyp_FLAG,
  /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,
  /* 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:  */ 7, 5,
  /* 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:  */ 43, 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_RecoveryMode },
#endif
};
/* Number of pragmas: 59 on by default, 73 total. */

**
** TF_OOOHidden applies to tables or view that have hidden columns that are
** followed by non-hidden columns.  Example:  "CREATE VIRTUAL TABLE x USING
** vtab1(a HIDDEN, b);".  Since "b" is a non-hidden column but "a" is hidden,
** the TF_OOOHidden attribute would apply in this case.  Such tables require
** special handling during INSERT processing.
*/
#define TF_Readonly        0x0001    /* Read-only system table */
#define TF_Ephemeral       0x0002    /* An ephemeral table */
#define TF_HasPrimaryKey   0x0004    /* Table has a primary key */
#define TF_Autoincrement   0x0008    /* Integer primary key is autoincrement */
#define TF_HasStat1        0x0010    /* Has STAT1 data */
#define TF_WithoutRowid    0x0020    /* No rowid.  PRIMARY KEY is the key */
#define TF_NoVisibleRowid  0x0040    /* No user-visible "rowid" column */
#define TF_OOOHidden       0x0080    /* Out-of-Order hidden columns */


/*
** Test to see whether or not a table is a virtual table.  This is
** done as a macro so that it will be optimized out when virtual
** table support is omitted from the build.
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE

  u8 onError;              /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  unsigned idxType:2;      /* 1==UNIQUE, 2==PRIMARY KEY, 0==CREATE INDEX */
  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;     /* True if stat1 data has been loaded */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  int nSample;             /* Number of elements in aSample[] */
  int nSampleCol;          /* Size of IndexSample.anEq[] and so on */
  tRowcnt *aAvgEq;         /* Average nEq values for keys not in aSample */
  IndexSample *aSample;    /* Samples of the left-most key */
  tRowcnt *aiRowEst;       /* Non-logarithmic stat1 data for this index */
  tRowcnt nRowEst0;        /* Non-logarithmic number of rows in the index */

  NAME: table_info
  FLAG: NeedSchema Result1 SchemaOpt
  COLS: cid name type notnull dflt_value pk
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)

  NAME: stats
  FLAG: NeedSchema Result0 SchemaReq
  COLS: table index width height flags
  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
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)