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Overview
Comment:An early attempt to get indexes to work with the IS operator. This code passes tests, but much more testing is needed to verify that it works on all corner cases.
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SHA1: 6f7f1673d00d216a5aa456acb44793a14f3b3d91
User & Date: drh 2015-05-13 15:24:07
Context
2015-05-13
17:54
Add testcase() macros and comments and a few test-cases. check-in: 24263d08 user: drh tags: index-is-operator
15:24
An early attempt to get indexes to work with the IS operator. This code passes tests, but much more testing is needed to verify that it works on all corner cases. check-in: 6f7f1673 user: drh tags: index-is-operator
04:50
Enhancements to the MSVC makefile. check-in: 59e3e9e7 user: mistachkin tags: trunk
Changes
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Changes to src/where.c.

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** "=", "<", ">", "<=", ">=", "IN", and "IS NULL"
*/
static int allowedOp(int op){
  assert( TK_GT>TK_EQ && TK_GT<TK_GE );
  assert( TK_LT>TK_EQ && TK_LT<TK_GE );
  assert( TK_LE>TK_EQ && TK_LE<TK_GE );
  assert( TK_GE==TK_EQ+4 );
  return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL;
}

/*
** Commute a comparison operator.  Expressions of the form "X op Y"
** are converted into "Y op X".
**
** If left/right precedence rules come into play when determining the
................................................................................
static u16 operatorMask(int op){
  u16 c;
  assert( allowedOp(op) );
  if( op==TK_IN ){
    c = WO_IN;
  }else if( op==TK_ISNULL ){
    c = WO_ISNULL;


  }else{
    assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
    c = (u16)(WO_EQ<<(op-TK_EQ));
  }
  assert( op!=TK_ISNULL || c==WO_ISNULL );
  assert( op!=TK_IN || c==WO_IN );
  assert( op!=TK_EQ || c==WO_EQ );
  assert( op!=TK_LT || c==WO_LT );
  assert( op!=TK_LE || c==WO_LE );
  assert( op!=TK_GT || c==WO_GT );
  assert( op!=TK_GE || c==WO_GE );

  return c;
}

/*
** Advance to the next WhereTerm that matches according to the criteria
** established when the pScan object was initialized by whereScanInit().
** Return NULL if there are no more matching WhereTerms.
................................................................................
    Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
    u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
    if( pLeft->op==TK_COLUMN ){
      pTerm->leftCursor = pLeft->iTable;
      pTerm->u.leftColumn = pLeft->iColumn;
      pTerm->eOperator = operatorMask(op) & opMask;
    }

    if( pRight && pRight->op==TK_COLUMN ){
      WhereTerm *pNew;
      Expr *pDup;
      u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
      if( pTerm->leftCursor>=0 ){
        int idxNew;
        pDup = sqlite3ExprDup(db, pExpr, 0);
................................................................................
        if( pExpr->op==TK_EQ
         && !ExprHasProperty(pExpr, EP_FromJoin)
         && OptimizationEnabled(db, SQLITE_Transitive)
        ){
          pTerm->eOperator |= WO_EQUIV;
          eExtraOp = WO_EQUIV;
        }

      }else{
        pDup = pExpr;
        pNew = pTerm;
      }
      exprCommute(pParse, pDup);
      pLeft = sqlite3ExprSkipCollate(pDup->pLeft);
      pNew->leftCursor = pLeft->iTable;
................................................................................

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  /* When sqlite_stat3 histogram data is available an operator of the
  ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
  ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
  ** virtual term of that form.
  **
  ** Note that the virtual term must be tagged with TERM_VNULL.  This
  ** TERM_VNULL tag will suppress the not-null check at the beginning
  ** of the loop.  Without the TERM_VNULL flag, the not-null check at
  ** the start of the loop will prevent any results from being returned.
  */
  if( pExpr->op==TK_NOTNULL
   && pExpr->pLeft->op==TK_COLUMN
   && pExpr->pLeft->iColumn>=0
   && OptimizationEnabled(db, SQLITE_Stat34)
  ){
    Expr *pNewExpr;
................................................................................
    WhereTerm *pNewTerm;

    pNewExpr = sqlite3PExpr(pParse, TK_GT,
                            sqlite3ExprDup(db, pLeft, 0),
                            sqlite3PExpr(pParse, TK_NULL, 0, 0, 0), 0);

    idxNew = whereClauseInsert(pWC, pNewExpr,
                              TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL);
    if( idxNew ){
      pNewTerm = &pWC->a[idxNew];
      pNewTerm->prereqRight = 0;
      pNewTerm->leftCursor = pLeft->iTable;
      pNewTerm->u.leftColumn = pLeft->iColumn;
      pNewTerm->eOperator = WO_GT;
      markTermAsChild(pWC, idxNew, idxTerm);
................................................................................
  int iTarget         /* Attempt to leave results in this register */
){
  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( iTarget>0 );
  if( pX->op==TK_EQ ){
    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType;
................................................................................
        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;

      if( sqlite3ExprCanBeNull(pRight) ){

        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
        VdbeCoverage(v);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
          zAff[j] = SQLITE_AFF_NONE;
        }
................................................................................

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
      if( (pRangeStart->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( zStartAff ){
        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){
................................................................................
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( sqlite3CompareAffinity(pRight, cEndAff)!=SQLITE_AFF_NONE
       && !sqlite3ExprNeedsNoAffinityChange(pRight, cEndAff)
................................................................................
    sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm);
  }else{
    char zType[4];
    memcpy(zType, "...", 4);
    if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V';
    if( pTerm->eOperator & WO_EQUIV  ) zType[1] = 'E';
    if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) zType[2] = 'L';

    sqlite3DebugPrintf("TERM-%-3d %p %s cursor=%-3d prob=%-3d op=0x%03x\n",
                       iTerm, pTerm, zType, pTerm->leftCursor, pTerm->truthProb,
                       pTerm->eOperator);
    sqlite3TreeViewExpr(0, pTerm->pExpr, 0);
  }
}
#endif

#ifdef WHERETRACE_ENABLED
/*







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** "=", "<", ">", "<=", ">=", "IN", and "IS NULL"
*/
static int allowedOp(int op){
  assert( TK_GT>TK_EQ && TK_GT<TK_GE );
  assert( TK_LT>TK_EQ && TK_LT<TK_GE );
  assert( TK_LE>TK_EQ && TK_LE<TK_GE );
  assert( TK_GE==TK_EQ+4 );
  return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL || op==TK_IS;
}

/*
** Commute a comparison operator.  Expressions of the form "X op Y"
** are converted into "Y op X".
**
** If left/right precedence rules come into play when determining the
................................................................................
static u16 operatorMask(int op){
  u16 c;
  assert( allowedOp(op) );
  if( op==TK_IN ){
    c = WO_IN;
  }else if( op==TK_ISNULL ){
    c = WO_ISNULL;
  }else if( op==TK_IS ){
    c = WO_EQ;
  }else{
    assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
    c = (u16)(WO_EQ<<(op-TK_EQ));
  }
  assert( op!=TK_ISNULL || c==WO_ISNULL );
  assert( op!=TK_IN || c==WO_IN );
  assert( op!=TK_EQ || c==WO_EQ );
  assert( op!=TK_LT || c==WO_LT );
  assert( op!=TK_LE || c==WO_LE );
  assert( op!=TK_GT || c==WO_GT );
  assert( op!=TK_GE || c==WO_GE );
  assert( op!=TK_IS || c==WO_EQ );
  return c;
}

/*
** Advance to the next WhereTerm that matches according to the criteria
** established when the pScan object was initialized by whereScanInit().
** Return NULL if there are no more matching WhereTerms.
................................................................................
    Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
    u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
    if( pLeft->op==TK_COLUMN ){
      pTerm->leftCursor = pLeft->iTable;
      pTerm->u.leftColumn = pLeft->iColumn;
      pTerm->eOperator = operatorMask(op) & opMask;
    }
    if( op==TK_IS ) pTerm->wtFlags |= TERM_NULLOK;
    if( pRight && pRight->op==TK_COLUMN ){
      WhereTerm *pNew;
      Expr *pDup;
      u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
      if( pTerm->leftCursor>=0 ){
        int idxNew;
        pDup = sqlite3ExprDup(db, pExpr, 0);
................................................................................
        if( pExpr->op==TK_EQ
         && !ExprHasProperty(pExpr, EP_FromJoin)
         && OptimizationEnabled(db, SQLITE_Transitive)
        ){
          pTerm->eOperator |= WO_EQUIV;
          eExtraOp = WO_EQUIV;
        }
        if( op==TK_IS ) pNew->wtFlags |= TERM_NULLOK;
      }else{
        pDup = pExpr;
        pNew = pTerm;
      }
      exprCommute(pParse, pDup);
      pLeft = sqlite3ExprSkipCollate(pDup->pLeft);
      pNew->leftCursor = pLeft->iTable;
................................................................................

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  /* When sqlite_stat3 histogram data is available an operator of the
  ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
  ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
  ** virtual term of that form.
  **
  ** Note that the virtual term must be tagged with both TERM_VNULL
  ** and TERM_NULLOK.


  */
  if( pExpr->op==TK_NOTNULL
   && pExpr->pLeft->op==TK_COLUMN
   && pExpr->pLeft->iColumn>=0
   && OptimizationEnabled(db, SQLITE_Stat34)
  ){
    Expr *pNewExpr;
................................................................................
    WhereTerm *pNewTerm;

    pNewExpr = sqlite3PExpr(pParse, TK_GT,
                            sqlite3ExprDup(db, pLeft, 0),
                            sqlite3PExpr(pParse, TK_NULL, 0, 0, 0), 0);

    idxNew = whereClauseInsert(pWC, pNewExpr,
                              TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL|TERM_NULLOK);
    if( idxNew ){
      pNewTerm = &pWC->a[idxNew];
      pNewTerm->prereqRight = 0;
      pNewTerm->leftCursor = pLeft->iTable;
      pNewTerm->u.leftColumn = pLeft->iColumn;
      pNewTerm->eOperator = WO_GT;
      markTermAsChild(pWC, idxNew, idxTerm);
................................................................................
  int iTarget         /* Attempt to leave results in this register */
){
  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( iTarget>0 );
  if( pX->op==TK_EQ || pX->op==TK_IS ){
    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType;
................................................................................
        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;
      if( (pTerm->wtFlags & TERM_NULLOK)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
        VdbeCoverage(v);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
          zAff[j] = SQLITE_AFF_NONE;
        }
................................................................................

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
      if( (pRangeStart->wtFlags & TERM_NULLOK)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( zStartAff ){
        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){
................................................................................
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
      if( (pRangeEnd->wtFlags & TERM_NULLOK)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( sqlite3CompareAffinity(pRight, cEndAff)!=SQLITE_AFF_NONE
       && !sqlite3ExprNeedsNoAffinityChange(pRight, cEndAff)
................................................................................
    sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm);
  }else{
    char zType[4];
    memcpy(zType, "...", 4);
    if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V';
    if( pTerm->eOperator & WO_EQUIV  ) zType[1] = 'E';
    if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) zType[2] = 'L';
    sqlite3DebugPrintf(
       "TERM-%-3d %p %s cursor=%-3d prob=%-3d op=0x%03x wtFlags=0x%04x\n",
       iTerm, pTerm, zType, pTerm->leftCursor, pTerm->truthProb,
       pTerm->eOperator, pTerm->wtFlags);
    sqlite3TreeViewExpr(0, pTerm->pExpr, 0);
  }
}
#endif

#ifdef WHERETRACE_ENABLED
/*

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#  define TERM_VNULL    0x80   /* Manufactured x>NULL or x<=NULL term */
#else
#  define TERM_VNULL    0x00   /* Disabled if not using stat3 */
#endif
#define TERM_LIKEOPT    0x100  /* Virtual terms from the LIKE optimization */
#define TERM_LIKECOND   0x200  /* Conditionally this LIKE operator term */
#define TERM_LIKE       0x400  /* The original LIKE operator */


/*
** An instance of the WhereScan object is used as an iterator for locating
** terms in the WHERE clause that are useful to the query planner.
*/
struct WhereScan {
  WhereClause *pOrigWC;      /* Original, innermost WhereClause */







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#  define TERM_VNULL    0x80   /* Manufactured x>NULL or x<=NULL term */
#else
#  define TERM_VNULL    0x00   /* Disabled if not using stat3 */
#endif
#define TERM_LIKEOPT    0x100  /* Virtual terms from the LIKE optimization */
#define TERM_LIKECOND   0x200  /* Conditionally this LIKE operator term */
#define TERM_LIKE       0x400  /* The original LIKE operator */
#define TERM_NULLOK     0x800  /* Comparison operators against NULL work */

/*
** An instance of the WhereScan object is used as an iterator for locating
** terms in the WHERE clause that are useful to the query planner.
*/
struct WhereScan {
  WhereClause *pOrigWC;      /* Original, innermost WhereClause */