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Overview
Comment:Avoid an unnecessary seek operation some corner-case skip-scan operations.
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SHA1: 2a6003a937a210dfc279e393d3a0b49d1f3ac92e
User & Date: drh 2016-02-22 23:14:11
Context
2016-02-22
23:44
Remove code not needed now that synchronous=OFF database files no longer trigger the use of a master journal. check-in: aa9f4c62 user: drh tags: trunk
23:14
Avoid an unnecessary seek operation some corner-case skip-scan operations. check-in: 2a6003a9 user: drh tags: trunk
21:19
Clearer presentation of the logic. No functional changes. Closed-Leaf check-in: a3dcf6db user: drh tags: skip-scan-improvement
16:04
Always use the sqlite3VdbeDeleteAuxdata() routine for clearing auxdata on function parameter, rather than having a separate deleteAuxdataFromFrame() for doing the job for trigger frames. check-in: 64386fa3 user: drh tags: trunk
Changes
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Changes to src/wherecode.c.

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    }else if( bSeekPastNull ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
      nConstraint++;
      startEq = 0;
      start_constraints = 1;
    }
    codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);





    op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
    assert( op!=0 );
    sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
    VdbeCoverage(v);
    VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
    VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
    VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
    VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
    VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
    VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );


    /* Load the value for the inequality constraint at the end of the
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;







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    }else if( bSeekPastNull ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
      nConstraint++;
      startEq = 0;
      start_constraints = 1;
    }
    codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);
    if( pLoop->nSkip>0 && nConstraint==pLoop->nSkip ){
      /* The skip-scan logic inside the call to codeAllEqualityConstraints()
      ** above has already left the cursor sitting on the correct row,
      ** so no further seeking is needed */
    }else{
      op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
      assert( op!=0 );
      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
      VdbeCoverage(v);
      VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
      VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
      VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
      VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
      VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
      VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );
    }

    /* Load the value for the inequality constraint at the end of the
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;