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Overview
Comment:When possible, use the multi-column samples in sqlite_stat4 to estimate the number of index rows scanned by a query plan.
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SHA1: 2973f5ca736c4a6f13c653d54b6a29d7cae8d0ed
User & Date: dan 2013-08-06 20:01:43
Context
2013-08-06
20:15
Fixes for builds without SQLITE_ENABLE_STAT4. check-in: 84999e27 user: dan tags: sqlite_stat4
20:01
When possible, use the multi-column samples in sqlite_stat4 to estimate the number of index rows scanned by a query plan. check-in: 2973f5ca user: dan tags: sqlite_stat4
2013-08-05
19:04
Modify the vdbe code generated by ANALYZE to use fewer memory cells and cursor slots. check-in: 4a51cf28 user: dan tags: sqlite_stat4
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/alter.c.

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    return;
  }

  /* Ensure the default expression is something that sqlite3ValueFromExpr()
  ** can handle (i.e. not CURRENT_TIME etc.)
  */
  if( pDflt ){
    sqlite3_value *pVal;
    if( sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_NONE, &pVal) ){
      db->mallocFailed = 1;
      return;
    }
    if( !pVal ){
      sqlite3ErrorMsg(pParse, "Cannot add a column with non-constant default");
      return;







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    return;
  }

  /* Ensure the default expression is something that sqlite3ValueFromExpr()
  ** can handle (i.e. not CURRENT_TIME etc.)
  */
  if( pDflt ){
    sqlite3_value *pVal = 0;
    if( sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_NONE, &pVal) ){
      db->mallocFailed = 1;
      return;
    }
    if( !pVal ){
      sqlite3ErrorMsg(pParse, "Cannot add a column with non-constant default");
      return;

Changes to src/sqliteInt.h.

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char *sqlite3StrAccumFinish(StrAccum*);
void sqlite3StrAccumReset(StrAccum*);
void sqlite3SelectDestInit(SelectDest*,int,int);
Expr *sqlite3CreateColumnExpr(sqlite3 *, SrcList *, int, int);

void sqlite3BackupRestart(sqlite3_backup *);
void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);





/*
** The interface to the LEMON-generated parser
*/
void *sqlite3ParserAlloc(void*(*)(size_t));
void sqlite3ParserFree(void*, void(*)(void*));
void sqlite3Parser(void*, int, Token, Parse*);







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char *sqlite3StrAccumFinish(StrAccum*);
void sqlite3StrAccumReset(StrAccum*);
void sqlite3SelectDestInit(SelectDest*,int,int);
Expr *sqlite3CreateColumnExpr(sqlite3 *, SrcList *, int, int);

void sqlite3BackupRestart(sqlite3_backup *);
void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);

int sqlite3Stat4ProbeSetValue(Parse*, UnpackedRecord*, Expr*, u8, int, int*);
void sqlite3Stat4ProbeFree(UnpackedRecord*);
int sqlite3Stat4ProbeNew(Parse*, Index*, UnpackedRecord**);

/*
** The interface to the LEMON-generated parser
*/
void *sqlite3ParserAlloc(void*(*)(size_t));
void sqlite3ParserFree(void*, void(*)(void*));
void sqlite3Parser(void*, int, Token, Parse*);

Changes to src/update.c.

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** on register iReg. This is used when an equivalent integer value is 
** stored in place of an 8-byte floating point value in order to save 
** space.
*/
void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i, int iReg){
  assert( pTab!=0 );
  if( !pTab->pSelect ){
    sqlite3_value *pValue;
    u8 enc = ENC(sqlite3VdbeDb(v));
    Column *pCol = &pTab->aCol[i];
    VdbeComment((v, "%s.%s", pTab->zName, pCol->zName));
    assert( i<pTab->nCol );
    sqlite3ValueFromExpr(sqlite3VdbeDb(v), pCol->pDflt, enc, 
                         pCol->affinity, &pValue);
    if( pValue ){







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** on register iReg. This is used when an equivalent integer value is 
** stored in place of an 8-byte floating point value in order to save 
** space.
*/
void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i, int iReg){
  assert( pTab!=0 );
  if( !pTab->pSelect ){
    sqlite3_value *pValue = 0;
    u8 enc = ENC(sqlite3VdbeDb(v));
    Column *pCol = &pTab->aCol[i];
    VdbeComment((v, "%s.%s", pTab->zName, pCol->zName));
    assert( i<pTab->nCol );
    sqlite3ValueFromExpr(sqlite3VdbeDb(v), pCol->pDflt, enc, 
                         pCol->affinity, &pValue);
    if( pValue ){

Changes to src/vdbemem.c.

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  if( p ){
    p->flags = MEM_Null;
    p->type = SQLITE_NULL;
    p->db = db;
  }
  return p;
}






/*
** Create a new sqlite3_value object, containing the value of pExpr.
**
** This only works for very simple expressions that consist of one constant
** token (i.e. "5", "5.1", "'a string'"). If the expression can
** be converted directly into a value, then the value is allocated and
................................................................................
    pExpr = pExpr->pLeft;
    op = pExpr->op;
    negInt = -1;
    zNeg = "-";
  }

  if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
    pVal = sqlite3ValueNew(db);
    if( pVal==0 ) goto no_mem;
    if( ExprHasProperty(pExpr, EP_IntValue) ){
      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
    }else{
      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
      if( zVal==0 ) goto no_mem;
      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
................................................................................
      }else{
        pVal->u.i = -pVal->u.i;
      }
      pVal->r = -pVal->r;
      sqlite3ValueApplyAffinity(pVal, affinity, enc);
    }
  }else if( op==TK_NULL ){
    pVal = sqlite3ValueNew(db);
    if( pVal==0 ) goto no_mem;
  }
#ifndef SQLITE_OMIT_BLOB_LITERAL
  else if( op==TK_BLOB ){
    int nVal;
    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
    assert( pExpr->u.zToken[1]=='\'' );
    pVal = sqlite3ValueNew(db);
    if( !pVal ) goto no_mem;
    zVal = &pExpr->u.zToken[2];
    nVal = sqlite3Strlen30(zVal)-1;
    assert( zVal[nVal]=='\'' );
    sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
                         0, SQLITE_DYNAMIC);
  }
................................................................................
  }
  *ppVal = pVal;
  return SQLITE_OK;

no_mem:
  db->mallocFailed = 1;
  sqlite3DbFree(db, zVal);
  sqlite3ValueFree(pVal);
  *ppVal = 0;
  return SQLITE_NOMEM;
}






























































































/*
** Change the string value of an sqlite3_value object
*/
void sqlite3ValueSetStr(
  sqlite3_value *v,     /* Value to be set */
  int n,                /* Length of string z */
  const void *z,        /* Text of the new string */







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  if( p ){
    p->flags = MEM_Null;
    p->type = SQLITE_NULL;
    p->db = db;
  }
  return p;
}

static sqlite3_value *valueNew(sqlite3 *db, sqlite3_value *pOld){
  if( pOld ) return pOld;
  return sqlite3ValueNew(db);
}

/*
** Create a new sqlite3_value object, containing the value of pExpr.
**
** This only works for very simple expressions that consist of one constant
** token (i.e. "5", "5.1", "'a string'"). If the expression can
** be converted directly into a value, then the value is allocated and
................................................................................
    pExpr = pExpr->pLeft;
    op = pExpr->op;
    negInt = -1;
    zNeg = "-";
  }

  if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
    pVal = valueNew(db, *ppVal);
    if( pVal==0 ) goto no_mem;
    if( ExprHasProperty(pExpr, EP_IntValue) ){
      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
    }else{
      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
      if( zVal==0 ) goto no_mem;
      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
................................................................................
      }else{
        pVal->u.i = -pVal->u.i;
      }
      pVal->r = -pVal->r;
      sqlite3ValueApplyAffinity(pVal, affinity, enc);
    }
  }else if( op==TK_NULL ){
    pVal = valueNew(db, *ppVal);
    if( pVal==0 ) goto no_mem;
  }
#ifndef SQLITE_OMIT_BLOB_LITERAL
  else if( op==TK_BLOB ){
    int nVal;
    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
    assert( pExpr->u.zToken[1]=='\'' );
    pVal = valueNew(db, *ppVal);
    if( !pVal ) goto no_mem;
    zVal = &pExpr->u.zToken[2];
    nVal = sqlite3Strlen30(zVal)-1;
    assert( zVal[nVal]=='\'' );
    sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
                         0, SQLITE_DYNAMIC);
  }
................................................................................
  }
  *ppVal = pVal;
  return SQLITE_OK;

no_mem:
  db->mallocFailed = 1;
  sqlite3DbFree(db, zVal);
  if( *ppVal==0 ) sqlite3ValueFree(pVal);
  *ppVal = 0;
  return SQLITE_NOMEM;
}

#ifdef SQLITE_ENABLE_STAT4
int sqlite3Stat4ProbeSetValue(
  Parse *pParse,                  /* Parse context */
  UnpackedRecord *pRec,           /* Set field in this probe */
  Expr *pExpr,                    /* The expression to extract a value from */
  u8 affinity,                    /* Affinity to use */
  int iVal,                       /* Array element to populate */
  int *pbOk                       /* OUT: True if value was extracted */
){
  int rc = SQLITE_OK;
  sqlite3_value *pVal = &pRec->aMem[iVal];

#if 0
  if( iVal>0 ){ *pbOk = 0; return SQLITE_OK; }
#endif

  if( !pExpr ){
    sqlite3VdbeMemSetNull((Mem*)pVal);
    *pbOk = 1;
  }else if( pExpr->op==TK_VARIABLE
        || (pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE)
  ){
    Vdbe *v;
    int iVar = pExpr->iColumn;
    sqlite3VdbeSetVarmask(pParse->pVdbe, iVar);
    if( v = pParse->pReprepare ){
      rc = sqlite3VdbeMemCopy((Mem*)pVal, &v->aVar[iVal-1]);
      if( rc==SQLITE_OK ){
        sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
      }
      pVal->db = pParse->db;
      *pbOk = 1;
      sqlite3VdbeMemStoreType((Mem*)pVal);
    }else{
      *pbOk = 0;
    }
  }else{
    sqlite3 *db = pRec->aMem[0].db;
    rc = sqlite3ValueFromExpr(db, pExpr, ENC(db), affinity, &pVal);
    *pbOk = (pVal!=0);
  }
  assert( pVal==0 || pVal->db==pParse->db );
  return rc;
}

void sqlite3Stat4ProbeFree(UnpackedRecord *pRec){
  if( pRec ){
    int i;
    Mem *aMem = pRec->aMem;
    sqlite3 *db = aMem[0].db;
    for(i=0; i<pRec->pKeyInfo->nField; i++){
      sqlite3DbFree(db, aMem[i].zMalloc);
    }
    sqlite3DbFree(db, pRec->pKeyInfo);
    sqlite3DbFree(db, pRec);
  }
}

int sqlite3Stat4ProbeNew(
  Parse *pParse,                  /* Parse context */
  Index *pIdx,                    /* Allocate record for this index */
  UnpackedRecord **ppRec          /* OUT: Allocated record */
){
  sqlite3 *db = pParse->db;       /* Database handle */
  UnpackedRecord *pRec;           /* Return value */
  int nByte;                      /* Bytes of space to allocate */
  int i;                          /* Counter variable */

  assert( *ppRec==0 );
  if( pIdx->nSample==0 ) return SQLITE_OK;

  nByte = sizeof(Mem) * pIdx->nColumn + sizeof(UnpackedRecord);
  *ppRec = pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
  if( !pRec ) return SQLITE_NOMEM;
  pRec->pKeyInfo = sqlite3IndexKeyinfo(pParse, pIdx);
  if( !pRec->pKeyInfo ){
    sqlite3DbFree(db, pRec);
    *ppRec = 0;
    return SQLITE_NOMEM;
  }
  pRec->pKeyInfo->enc = ENC(pParse->db);
  pRec->flags = UNPACKED_PREFIX_MATCH;
  pRec->aMem = (Mem *)&pRec[1];
  for(i=0; i<pIdx->nColumn; i++){
    pRec->aMem[i].flags = MEM_Null;
    pRec->aMem[i].type = SQLITE_NULL;
    pRec->aMem[i].db = db;
  }

  return SQLITE_OK;
}
#endif /* ifdef SQLITE_ENABLE_STAT4 */

/*
** Change the string value of an sqlite3_value object
*/
void sqlite3ValueSetStr(
  sqlite3_value *v,     /* Value to be set */
  int n,                /* Length of string z */
  const void *z,        /* Text of the new string */

Changes to src/where.c.

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*/
struct WhereLoopBuilder {
  WhereInfo *pWInfo;        /* Information about this WHERE */
  WhereClause *pWC;         /* WHERE clause terms */
  ExprList *pOrderBy;       /* ORDER BY clause */
  WhereLoop *pNew;          /* Template WhereLoop */
  WhereOrSet *pOrSet;       /* Record best loops here, if not NULL */





};

/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second
** half does the tail of the WHERE loop.  An instance of
** this structure is returned by the first half and passed
................................................................................
**    aStat[1]      Est. number of rows equal to pVal
**
** Return SQLITE_OK on success.
*/
static int whereKeyStats(
  Parse *pParse,              /* Database connection */
  Index *pIdx,                /* Index to consider domain of */
  sqlite3_value *pVal,        /* Value to consider */
  int roundUp,                /* Round up if true.  Round down if false */
  tRowcnt *aStat              /* OUT: stats written here */
){
  IndexSample *aSample = pIdx->aSample;
  UnpackedRecord rec;
  int i;
  int isEq = 0;

  if( pVal==0 ) return SQLITE_ERROR;

  memset(&rec, 0, sizeof(UnpackedRecord));
  rec.pKeyInfo = sqlite3IndexKeyinfo(pParse, pIdx);
  if( rec.pKeyInfo==0 ) return SQLITE_NOMEM;
  rec.pKeyInfo->enc = ENC(pParse->db);
  rec.nField = 1;
  rec.flags = UNPACKED_PREFIX_MATCH;
  rec.aMem = pVal;

  for(i=0; i<pIdx->nSample; i++){
    int res = sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, &rec);
    if( res>=0 ){
      isEq = (res==0);
      break;
    }
  }
  sqlite3DbFree(pParse->db, rec.pKeyInfo);

  /* At this point, aSample[i] is the first sample that is greater than
  ** or equal to pVal.  Or if i==pIdx->nSample, then all samples are less
  ** than pVal.  If aSample[i]==pVal, then isEq==1.
  */
  if( isEq ){
    assert( i<pIdx->nSample );
................................................................................
    }
    aStat[0] = iLower + iGap;
  }
  return SQLITE_OK;
}
#endif /* SQLITE_ENABLE_STAT4 */

/*
** If expression pExpr represents a literal value, set *pp to point to
** an sqlite3_value structure containing the same value, with affinity
** aff applied to it, before returning. It is the responsibility of the 
** caller to eventually release this structure by passing it to 
** sqlite3ValueFree().
**
** If the current parse is a recompile (sqlite3Reprepare()) and pExpr
** is an SQL variable that currently has a non-NULL value bound to it,
** create an sqlite3_value structure containing this value, again with
** affinity aff applied to it, instead.
**
** If neither of the above apply, set *pp to NULL.
**
** If an error occurs, return an error code. Otherwise, SQLITE_OK.
*/
#ifdef SQLITE_ENABLE_STAT4
static int valueFromExpr(
  Parse *pParse, 
  Expr *pExpr, 
  u8 aff, 
  sqlite3_value **pp
){
  if( pExpr->op==TK_VARIABLE
   || (pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE)
  ){
    int iVar = pExpr->iColumn;
    sqlite3VdbeSetVarmask(pParse->pVdbe, iVar);
    *pp = sqlite3VdbeGetBoundValue(pParse->pReprepare, iVar, aff);
    return SQLITE_OK;
  }
  return sqlite3ValueFromExpr(pParse->db, pExpr, ENC(pParse->db), aff, pp);
}
#endif

/*
** This function is used to estimate the number of rows that will be visited
** by scanning an index for a range of values. The range may have an upper
** bound, a lower bound, or both. The WHERE clause terms that set the upper
** and lower bounds are represented by pLower and pUpper respectively. For
** example, assuming that index p is on t1(a):
**
................................................................................
** In the absence of sqlite_stat3 ANALYZE data, each range inequality
** reduces the search space by a factor of 4.  Hence a single constraint (x>?)
** results in a return of 4 and a range constraint (x>? AND x<?) results
** in a return of 16.
*/
static int whereRangeScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index containing the range-compared column; "x" */
  int nEq,             /* index into p->aCol[] of the range-compared column */
  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
  WhereCost *pRangeDiv /* OUT: Reduce search space by this divisor */
){
  int rc = SQLITE_OK;

#ifdef SQLITE_ENABLE_STAT4





  if( nEq==0 && p->nSample && OptimizationEnabled(pParse->db, SQLITE_Stat3) ){
    sqlite3_value *pRangeVal;


    tRowcnt iLower = 0;
    tRowcnt iUpper = p->aiRowEst[0];
    tRowcnt a[2];
    u8 aff = p->pTable->aCol[p->aiColumn[0]].affinity;

    if( pLower ){

      Expr *pExpr = pLower->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pRangeVal);
      assert( (pLower->eOperator & (WO_GT|WO_GE))!=0 );


      if( rc==SQLITE_OK
       && whereKeyStats(pParse, p, pRangeVal, 0, a)==SQLITE_OK
      ){
        iLower = a[0];
        if( (pLower->eOperator & WO_GT)!=0 ) iLower += a[1];
      }
      sqlite3ValueFree(pRangeVal);
    }
    if( rc==SQLITE_OK && pUpper ){

      Expr *pExpr = pUpper->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pRangeVal);
      assert( (pUpper->eOperator & (WO_LT|WO_LE))!=0 );


      if( rc==SQLITE_OK
       && whereKeyStats(pParse, p, pRangeVal, 1, a)==SQLITE_OK
      ){
        iUpper = a[0];
        if( (pUpper->eOperator & WO_LE)!=0 ) iUpper += a[1];
      }
      sqlite3ValueFree(pRangeVal);
    }
    if( rc==SQLITE_OK ){
      WhereCost iBase = whereCost(p->aiRowEst[0]);
      if( iUpper>iLower ){
        iBase -= whereCost(iUpper - iLower);
      }



      *pRangeDiv = iBase;

      WHERETRACE(0x100, ("range scan regions: %u..%u  div=%d\n",
                         (u32)iLower, (u32)iUpper, *pRangeDiv));
      return SQLITE_OK;
    }
  }
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(p);
  UNUSED_PARAMETER(nEq);
#endif
  assert( pLower || pUpper );
  *pRangeDiv = 0;
  /* TUNING:  Each inequality constraint reduces the search space 4-fold.
  ** A BETWEEN operator, therefore, reduces the search space 16-fold */
  if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ){
................................................................................
** This routine can fail if it is unable to load a collating sequence
** required for string comparison, or if unable to allocate memory
** for a UTF conversion required for comparison.  The error is stored
** in the pParse structure.
*/
static int whereEqualScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index whose left-most column is pTerm */
  Expr *pExpr,         /* Expression for VALUE in the x=VALUE constraint */
  tRowcnt *pnRow       /* Write the revised row estimate here */
){
  sqlite3_value *pRhs = 0;  /* VALUE on right-hand side of pTerm */


  u8 aff;                   /* Column affinity */
  int rc;                   /* Subfunction return code */
  tRowcnt a[2];             /* Statistics */




  assert( p->aSample!=0 );
  assert( p->nSample>0 );













  aff = p->pTable->aCol[p->aiColumn[0]].affinity;
  if( pExpr ){
    rc = valueFromExpr(pParse, pExpr, aff, &pRhs);
    if( rc ) goto whereEqualScanEst_cancel;
  }else{
    pRhs = sqlite3ValueNew(pParse->db);



  }
  if( pRhs==0 ) return SQLITE_NOTFOUND;



  rc = whereKeyStats(pParse, p, pRhs, 0, a);
  if( rc==SQLITE_OK ){
    WHERETRACE(0x100,("equality scan regions: %d\n", (int)a[1]));
    *pnRow = a[1];


  }
whereEqualScanEst_cancel:
  sqlite3ValueFree(pRhs);


  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT4) */

#ifdef SQLITE_ENABLE_STAT4
/*
** Estimate the number of rows that will be returned based on
................................................................................
** This routine can fail if it is unable to load a collating sequence
** required for string comparison, or if unable to allocate memory
** for a UTF conversion required for comparison.  The error is stored
** in the pParse structure.
*/
static int whereInScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index whose left-most column is pTerm */
  ExprList *pList,     /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
  tRowcnt *pnRow       /* Write the revised row estimate here */
){


  int rc = SQLITE_OK;     /* Subfunction return code */
  tRowcnt nEst;           /* Number of rows for a single term */
  tRowcnt nRowEst = 0;    /* New estimate of the number of rows */
  int i;                  /* Loop counter */

  assert( p->aSample!=0 );
  for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){
    nEst = p->aiRowEst[0];
    rc = whereEqualScanEst(pParse, p, pList->a[i].pExpr, &nEst);
    nRowEst += nEst;

  }

  if( rc==SQLITE_OK ){
    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];



    *pnRow = nRowEst;

    WHERETRACE(0x100,("IN row estimate: est=%g\n", nRowEst));
  }

  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT4) */

/*
** Disable a term in the WHERE clause.  Except, do not disable the term
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
................................................................................
  saved_wsFlags = pNew->wsFlags;
  saved_prereq = pNew->prereq;
  saved_nOut = pNew->nOut;
  pNew->rSetup = 0;
  rLogSize = estLog(whereCost(pProbe->aiRowEst[0]));
  for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
    int nIn = 0;
    if( pTerm->prereqRight & pNew->maskSelf ) continue;
#ifdef SQLITE_ENABLE_STAT4


    if( (pTerm->wtFlags & TERM_VNULL)!=0 && pSrc->pTab->aCol[iCol].notNull ){
      continue; /* skip IS NOT NULL constraints on a NOT NULL column */
    }
#endif


    pNew->wsFlags = saved_wsFlags;
    pNew->u.btree.nEq = saved_nEq;
    pNew->nLTerm = saved_nLTerm;
    if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
    pNew->aLTerm[pNew->nLTerm++] = pTerm;
    pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf;
    pNew->rRun = rLogSize; /* Baseline cost is log2(N).  Adjustments below */
................................................................................
      pTop = pTerm;
      pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ?
                     pNew->aLTerm[pNew->nLTerm-2] : 0;
    }
    if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
      /* Adjust nOut and rRun for STAT3 range values */
      WhereCost rDiv;
      whereRangeScanEst(pParse, pProbe, pNew->u.btree.nEq,
                        pBtm, pTop, &rDiv);
      pNew->nOut = saved_nOut>rDiv+10 ? saved_nOut - rDiv : 10;
    }
#ifdef SQLITE_ENABLE_STAT4
    if( pNew->u.btree.nEq==1 && pProbe->nSample
     &&  OptimizationEnabled(db, SQLITE_Stat3) ){
      tRowcnt nOut = 0;
      if( (pTerm->eOperator & (WO_EQ|WO_ISNULL))!=0 ){
        testcase( pTerm->eOperator & WO_EQ );
        testcase( pTerm->eOperator & WO_ISNULL );
        rc = whereEqualScanEst(pParse, pProbe, pTerm->pExpr->pRight, &nOut);


      }else if( (pTerm->eOperator & WO_IN)
             &&  !ExprHasProperty(pTerm->pExpr, EP_xIsSelect)  ){
        rc = whereInScanEst(pParse, pProbe, pTerm->pExpr->x.pList, &nOut);
      }
      assert( nOut==0 || rc==SQLITE_OK );
      if( nOut ) pNew->nOut = whereCost(nOut);
    }
#endif
    if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
      /* Each row involves a step of the index, then a binary search of
................................................................................
    /* TBD: Adjust nOut for additional constraints */
    rc = whereLoopInsert(pBuilder, pNew);
    if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
     && pNew->u.btree.nEq<(pProbe->nColumn + (pProbe->zName!=0))
    ){
      whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
    }




  }
  pNew->prereq = saved_prereq;
  pNew->u.btree.nEq = saved_nEq;
  pNew->wsFlags = saved_wsFlags;
  pNew->nOut = saved_nOut;
  pNew->nLTerm = saved_nLTerm;
  return rc;
................................................................................
          ** which we will simplify to just N*log2(N) */
          pNew->rRun = rSize + rLogSize;
        }
        rc = whereLoopInsert(pBuilder, pNew);
        if( rc ) break;
      }
    }




    rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0);






    /* If there was an INDEXED BY clause, then only that one index is
    ** considered. */
    if( pSrc->pIndex ) break;
  }
  return rc;
}







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386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
....
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417

2418
2419
2420










2421
2422
2423
2424
2425
2426
2427

2428
2429
2430
2431
2432
2433
2434
....
2456
2457
2458
2459
2460
2461
2462



































2463
2464
2465
2466
2467
2468
2469
....
2497
2498
2499
2500
2501
2502
2503
2504

2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517

2518
2519
2520
2521
2522
2523

2524
2525
2526

2527
2528
2529
2530
2531
2532
2533
2534
2535

2536
2537
2538
2539

2540
2541
2542
2543
2544
2545
2546
2547
2548

2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
....
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632





2633
2634
2635
2636

2637
2638
2639
2640
2641
2642
2643
2644
2645
2646


2647
2648
2649
2650
2651
2652
2653
2654
2655
....
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
....
4240
4241
4242
4243
4244
4245
4246

4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
....
4306
4307
4308
4309
4310
4311
4312

4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
....
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
....
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
*/
struct WhereLoopBuilder {
  WhereInfo *pWInfo;        /* Information about this WHERE */
  WhereClause *pWC;         /* WHERE clause terms */
  ExprList *pOrderBy;       /* ORDER BY clause */
  WhereLoop *pNew;          /* Template WhereLoop */
  WhereOrSet *pOrSet;       /* Record best loops here, if not NULL */
#ifdef SQLITE_ENABLE_STAT4
  UnpackedRecord *pRec;     /* Probe for stat4 (if required) */
  int nRecValid;            /* Number of valid fields currently in pRec */
  tRowcnt nMaxRowcnt;       /* If !=0, the maximum estimated row count */
#endif
};

/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second
** half does the tail of the WHERE loop.  An instance of
** this structure is returned by the first half and passed
................................................................................
**    aStat[1]      Est. number of rows equal to pVal
**
** Return SQLITE_OK on success.
*/
static int whereKeyStats(
  Parse *pParse,              /* Database connection */
  Index *pIdx,                /* Index to consider domain of */
  UnpackedRecord *pRec,       /* Vector of values to consider */
  int roundUp,                /* Round up if true.  Round down if false */
  tRowcnt *aStat              /* OUT: stats written here */
){
  IndexSample *aSample = pIdx->aSample;

  int i;
  int isEq = 0;











  for(i=0; i<pIdx->nSample; i++){
    int res = sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec);
    if( res>=0 ){
      isEq = (res==0);
      break;
    }
  }


  /* At this point, aSample[i] is the first sample that is greater than
  ** or equal to pVal.  Or if i==pIdx->nSample, then all samples are less
  ** than pVal.  If aSample[i]==pVal, then isEq==1.
  */
  if( isEq ){
    assert( i<pIdx->nSample );
................................................................................
    }
    aStat[0] = iLower + iGap;
  }
  return SQLITE_OK;
}
#endif /* SQLITE_ENABLE_STAT4 */




































/*
** This function is used to estimate the number of rows that will be visited
** by scanning an index for a range of values. The range may have an upper
** bound, a lower bound, or both. The WHERE clause terms that set the upper
** and lower bounds are represented by pLower and pUpper respectively. For
** example, assuming that index p is on t1(a):
**
................................................................................
** In the absence of sqlite_stat3 ANALYZE data, each range inequality
** reduces the search space by a factor of 4.  Hence a single constraint (x>?)
** results in a return of 4 and a range constraint (x>? AND x<?) results
** in a return of 16.
*/
static int whereRangeScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  WhereLoopBuilder *pBuilder,

  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
  WhereCost *pRangeDiv /* OUT: Reduce search space by this divisor */
){
  int rc = SQLITE_OK;

#ifdef SQLITE_ENABLE_STAT4
  Index *p = pBuilder->pNew->u.btree.pIndex;
  int nEq = pBuilder->pNew->u.btree.nEq;

  if( nEq==pBuilder->nRecValid 
   && p->nSample 
   && OptimizationEnabled(pParse->db, SQLITE_Stat3) 

  ){
    UnpackedRecord *pRec = pBuilder->pRec;
    tRowcnt iLower = 0;
    tRowcnt iUpper = p->aiRowEst[0];
    tRowcnt a[2];
    u8 aff = p->pTable->aCol[p->aiColumn[0]].affinity;

    if( pLower ){
      int bOk;                    /* True if value is extracted from pExpr */
      Expr *pExpr = pLower->pExpr->pRight;

      assert( (pLower->eOperator & (WO_GT|WO_GE))!=0 );
      rc = sqlite3Stat4ProbeSetValue(pParse, pRec, pExpr, aff, nEq, &bOk);
      pRec->nField = nEq+1;
      if( rc==SQLITE_OK && bOk
       && whereKeyStats(pParse, p, pRec, 0, a)==SQLITE_OK
      ){
        iLower = a[0];
        if( (pLower->eOperator & WO_GT)!=0 ) iLower += a[1];
      }

    }
    if( rc==SQLITE_OK && pUpper ){
      int bOk;                    /* True if value is extracted from pExpr */
      Expr *pExpr = pUpper->pExpr->pRight;

      assert( (pUpper->eOperator & (WO_LT|WO_LE))!=0 );
      rc = sqlite3Stat4ProbeSetValue(pParse, pRec, pExpr, aff, nEq, &bOk);
      pRec->nField = nEq+1;
      if( rc==SQLITE_OK && bOk
       && whereKeyStats(pParse, p, pRec, 1, a)==SQLITE_OK
      ){
        iUpper = a[0];
        if( (pUpper->eOperator & WO_LE)!=0 ) iUpper += a[1];
      }

    }
    if( rc==SQLITE_OK ){
      WhereCost iBase = whereCost(p->aiRowEst[0]);
      if( iUpper>iLower ){
        iBase -= whereCost(iUpper - iLower);
      }
      if( pBuilder->nMaxRowcnt && iBase<pBuilder->nMaxRowcnt ){
        *pRangeDiv = pBuilder->nMaxRowcnt;
      }else{
        *pRangeDiv = iBase;
      }
      WHERETRACE(0x100, ("range scan regions: %u..%u  div=%d\n",
                         (u32)iLower, (u32)iUpper, *pRangeDiv));
      return SQLITE_OK;
    }
  }
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(pBuilder);
  UNUSED_PARAMETER(nEq);
#endif
  assert( pLower || pUpper );
  *pRangeDiv = 0;
  /* TUNING:  Each inequality constraint reduces the search space 4-fold.
  ** A BETWEEN operator, therefore, reduces the search space 16-fold */
  if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ){
................................................................................
** This routine can fail if it is unable to load a collating sequence
** required for string comparison, or if unable to allocate memory
** for a UTF conversion required for comparison.  The error is stored
** in the pParse structure.
*/
static int whereEqualScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  WhereLoopBuilder *pBuilder,
  Expr *pExpr,         /* Expression for VALUE in the x=VALUE constraint */
  tRowcnt *pnRow       /* Write the revised row estimate here */
){
  Index *p = pBuilder->pNew->u.btree.pIndex;
  int nEq = pBuilder->pNew->u.btree.nEq;
  UnpackedRecord *pRec = pBuilder->pRec;
  u8 aff;                   /* Column affinity */
  int rc;                   /* Subfunction return code */
  tRowcnt a[2];             /* Statistics */
  int bOk;

  assert( nEq>=1 );
  assert( nEq<=(p->nColumn+1) );
  assert( p->aSample!=0 );
  assert( p->nSample>0 );
  assert( pBuilder->nRecValid<nEq );

  /* If values are not available for all fields of the index to the left
  ** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */
  if( pBuilder->nRecValid<(nEq-1) ){
    return SQLITE_NOTFOUND;
  }

  if( nEq>p->nColumn ){
    *pnRow = 1;
    return SQLITE_OK;
  }

  aff = p->pTable->aCol[p->aiColumn[0]].affinity;





  rc = sqlite3Stat4ProbeSetValue(pParse, pRec, pExpr, aff, nEq-1, &bOk);
  if( rc!=SQLITE_OK ) return rc;
  if( bOk==0 ) return SQLITE_NOTFOUND;


  pBuilder->nRecValid = nEq;
  pRec->nField = nEq;

  rc = whereKeyStats(pParse, p, pRec, 0, a);
  if( rc==SQLITE_OK ){
    WHERETRACE(0x100,("equality scan regions: %d\n", (int)a[1]));
    *pnRow = a[1];
    if( pBuilder->nMaxRowcnt && *pnRow>pBuilder->nMaxRowcnt ){
      *pnRow = pBuilder->nMaxRowcnt;
    }


  }

  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT4) */

#ifdef SQLITE_ENABLE_STAT4
/*
** Estimate the number of rows that will be returned based on
................................................................................
** This routine can fail if it is unable to load a collating sequence
** required for string comparison, or if unable to allocate memory
** for a UTF conversion required for comparison.  The error is stored
** in the pParse structure.
*/
static int whereInScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  WhereLoopBuilder *pBuilder,
  ExprList *pList,     /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
  tRowcnt *pnRow       /* Write the revised row estimate here */
){
  Index *p = pBuilder->pNew->u.btree.pIndex;
  int nRecValid = pBuilder->nRecValid;
  int rc = SQLITE_OK;     /* Subfunction return code */
  tRowcnt nEst;           /* Number of rows for a single term */
  tRowcnt nRowEst = 0;    /* New estimate of the number of rows */
  int i;                  /* Loop counter */

  assert( p->aSample!=0 );
  for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){
    nEst = p->aiRowEst[0];
    rc = whereEqualScanEst(pParse, pBuilder, pList->a[i].pExpr, &nEst);
    nRowEst += nEst;
    pBuilder->nRecValid = nRecValid;
  }

  if( rc==SQLITE_OK ){
    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];
    if( pBuilder->nMaxRowcnt && nRowEst>pBuilder->nMaxRowcnt ){
      *pnRow = pBuilder->nMaxRowcnt;
    }else{
      *pnRow = nRowEst;
    }
    WHERETRACE(0x100,("IN row estimate: est=%g\n", nRowEst));
  }
  assert( pBuilder->nRecValid==nRecValid );
  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT4) */

/*
** Disable a term in the WHERE clause.  Except, do not disable the term
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
................................................................................
  saved_wsFlags = pNew->wsFlags;
  saved_prereq = pNew->prereq;
  saved_nOut = pNew->nOut;
  pNew->rSetup = 0;
  rLogSize = estLog(whereCost(pProbe->aiRowEst[0]));
  for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
    int nIn = 0;

#ifdef SQLITE_ENABLE_STAT4
    int nRecValid = pBuilder->nRecValid;
    int nMaxRowcnt = pBuilder->nMaxRowcnt;
    if( (pTerm->wtFlags & TERM_VNULL)!=0 && pSrc->pTab->aCol[iCol].notNull ){
      continue; /* skip IS NOT NULL constraints on a NOT NULL column */
    }
#endif
    if( pTerm->prereqRight & pNew->maskSelf ) continue;

    pNew->wsFlags = saved_wsFlags;
    pNew->u.btree.nEq = saved_nEq;
    pNew->nLTerm = saved_nLTerm;
    if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
    pNew->aLTerm[pNew->nLTerm++] = pTerm;
    pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf;
    pNew->rRun = rLogSize; /* Baseline cost is log2(N).  Adjustments below */
................................................................................
      pTop = pTerm;
      pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ?
                     pNew->aLTerm[pNew->nLTerm-2] : 0;
    }
    if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
      /* Adjust nOut and rRun for STAT3 range values */
      WhereCost rDiv;

      whereRangeScanEst(pParse, pBuilder, pBtm, pTop, &rDiv);
      pNew->nOut = saved_nOut>rDiv+10 ? saved_nOut - rDiv : 10;
    }
#ifdef SQLITE_ENABLE_STAT4
    if( nInMul==0 && pProbe->nSample && OptimizationEnabled(db, SQLITE_Stat3) ){
      Expr *pExpr = pTerm->pExpr;
      tRowcnt nOut = 0;
      if( (pTerm->eOperator & (WO_EQ|WO_ISNULL))!=0 ){
        testcase( pTerm->eOperator & WO_EQ );
        testcase( pTerm->eOperator & WO_ISNULL );
        rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut);
        assert( nOut==0||pBuilder->nMaxRowcnt==0||nOut<=pBuilder->nMaxRowcnt);
        if( nOut ) pBuilder->nMaxRowcnt = nOut;
      }else if( (pTerm->eOperator & WO_IN)
             &&  !ExprHasProperty(pExpr, EP_xIsSelect)  ){
        rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut);
      }
      assert( nOut==0 || rc==SQLITE_OK );
      if( nOut ) pNew->nOut = whereCost(nOut);
    }
#endif
    if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
      /* Each row involves a step of the index, then a binary search of
................................................................................
    /* TBD: Adjust nOut for additional constraints */
    rc = whereLoopInsert(pBuilder, pNew);
    if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
     && pNew->u.btree.nEq<(pProbe->nColumn + (pProbe->zName!=0))
    ){
      whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
    }
#ifdef SQLITE_ENABLE_STAT4
    pBuilder->nRecValid = nRecValid;
    pBuilder->nMaxRowcnt = nMaxRowcnt;
#endif
  }
  pNew->prereq = saved_prereq;
  pNew->u.btree.nEq = saved_nEq;
  pNew->wsFlags = saved_wsFlags;
  pNew->nOut = saved_nOut;
  pNew->nLTerm = saved_nLTerm;
  return rc;
................................................................................
          ** which we will simplify to just N*log2(N) */
          pNew->rRun = rSize + rLogSize;
        }
        rc = whereLoopInsert(pBuilder, pNew);
        if( rc ) break;
      }
    }

    assert( pBuilder->pRec==0 );
    rc = sqlite3Stat4ProbeNew(pWInfo->pParse, pProbe, &pBuilder->pRec);
    if( rc==SQLITE_OK ){
      rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0);
      sqlite3Stat4ProbeFree(pBuilder->pRec);
      pBuilder->nRecValid = 0;
      pBuilder->pRec = 0;
    }
    assert( pBuilder->pRec==0 );

    /* If there was an INDEXED BY clause, then only that one index is
    ** considered. */
    if( pSrc->pIndex ) break;
  }
  return rc;
}