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Comment:Strengthen check-in [83da4d4104ee1870] by ignoring *all* WHERE-clause constraints for a virtual table that is the right table of a LEFT JOIN, as such constraints are never useful. This fixes an issue discovered by Manuel Rigger.
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SHA3-256: 840de36df1aaeb4bad9a7c18e97cc560ba3b8c629c4520a05bc456d67b3347b9
User & Date: drh 2019-12-11 16:22:53
Context
2019-12-11
18:53
Improved tracing output from the LEMON-generated parser. (check-in: 4d6d2fc0 user: drh tags: trunk)
16:22
Strengthen check-in [83da4d4104ee1870] by ignoring *all* WHERE-clause constraints for a virtual table that is the right table of a LEFT JOIN, as such constraints are never useful. This fixes an issue discovered by Manuel Rigger. (check-in: 840de36d user: drh tags: trunk)
15:07
When trying to drop a virtual table that has no xDestroy method, invoke the xDisconnect method rather than doing nothing, to avoid a memory leak. (check-in: 1fa29a5f user: drh tags: trunk)
Changes
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Changes to src/where.c.

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    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
    testcase( pTerm->eOperator & WO_IN );
    testcase( pTerm->eOperator & WO_IS );
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_ALL );
    if( (pTerm->eOperator & ~(WO_EQUIV))==0 ) continue;
    if( pTerm->wtFlags & TERM_VNULL ) continue;




    if( (pSrc->fg.jointype & JT_LEFT)!=0
     && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
     && (pTerm->eOperator & (WO_IS|WO_ISNULL))
    ){
      /* An "IS" term in the WHERE clause where the virtual table is the rhs
      ** of a LEFT JOIN. Do not pass this term to the virtual table
      ** implementation, as this can lead to incorrect results from SQL such
      ** as:
      **
      **   "LEFT JOIN vtab WHERE vtab.col IS NULL"  */
      testcase( pTerm->eOperator & WO_ISNULL );
      testcase( pTerm->eOperator & WO_IS );
      continue;
    }
    assert( pTerm->u.leftColumn>=(-1) );
    pIdxCons[j].iColumn = pTerm->u.leftColumn;
    pIdxCons[j].iTermOffset = i;
    op = pTerm->eOperator & WO_ALL;
    if( op==WO_IN ) op = WO_EQ;
................................................................................
    }
    if( pTerm->prereqRight & pNew->maskSelf ) continue;

    /* Do not allow the upper bound of a LIKE optimization range constraint
    ** to mix with a lower range bound from some other source */
    if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue;

    /* Do not allow constraints from the WHERE clause to be used by the
    ** right table of a LEFT JOIN.  Only constraints in the ON clause are
    ** allowed */
    if( (pSrc->fg.jointype & JT_LEFT)!=0
     && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
    ){
      continue;
    }

    if( IsUniqueIndex(pProbe) && saved_nEq==pProbe->nKeyCol-1 ){







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    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
    testcase( pTerm->eOperator & WO_IN );
    testcase( pTerm->eOperator & WO_IS );
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_ALL );
    if( (pTerm->eOperator & ~(WO_EQUIV))==0 ) continue;
    if( pTerm->wtFlags & TERM_VNULL ) continue;

    /* tag-20191211-002: WHERE-clause constraints are not useful to the
    ** right-hand table of a LEFT JOIN.  See tag-20191211-001 for the
    ** equivalent restriction for ordinary tables. */
    if( (pSrc->fg.jointype & JT_LEFT)!=0
     && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)

    ){








      continue;
    }
    assert( pTerm->u.leftColumn>=(-1) );
    pIdxCons[j].iColumn = pTerm->u.leftColumn;
    pIdxCons[j].iTermOffset = i;
    op = pTerm->eOperator & WO_ALL;
    if( op==WO_IN ) op = WO_EQ;
................................................................................
    }
    if( pTerm->prereqRight & pNew->maskSelf ) continue;

    /* Do not allow the upper bound of a LIKE optimization range constraint
    ** to mix with a lower range bound from some other source */
    if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue;

    /* tag-20191211-001:  Do not allow constraints from the WHERE clause to
    ** be used by the right table of a LEFT JOIN.  Only constraints in the
    ** ON clause are allowed.  See tag-20191211-002 for the vtab equivalent. */
    if( (pSrc->fg.jointype & JT_LEFT)!=0
     && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
    ){
      continue;
    }

    if( IsUniqueIndex(pProbe) && saved_nEq==pProbe->nKeyCol-1 ){