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Overview
Comment:Clarify the computation of compatible isOrdered by in the plan solver of the query planner.
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Timelines: family | ancestors | descendants | both | query-planner-fix
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SHA1: b5e8fd575a80334160de0aac8084ed5cd28816a5
User & Date: drh 2014-08-07 20:37:01.008
Context
2014-08-07
20:42
When the estimated sorting cost overwhelms the estimated lookup cost, ensure that lookup costs are still taken into account when selecting a lookup algorithm. (check-in: 2af630c572 user: drh tags: trunk)
20:37
Clarify the computation of compatible isOrdered by in the plan solver of the query planner. (Closed-Leaf check-in: b5e8fd575a user: drh tags: query-planner-fix)
20:25
Remove the extraneous debugging printf() from the previous check-in. (check-in: 8f04d2c008 user: drh tags: query-planner-fix)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/where.c.
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        }
        /* Check to see if pWLoop should be added to the set of
        ** mxChoice best-so-far paths.
        **
        ** First look for an existing path among best-so-far paths
        ** that covers the same set of loops and has the same isOrdered
        ** setting as the current path candidate.




        */
        for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){
          if( pTo->maskLoop==maskNew
           && ((pTo->isOrdered^isOrdered)&80)==0
          ){
            testcase( jj==nTo-1 );
            break;
          }
        }
        if( jj>=nTo ){
          /* None of the existing best-so-far paths match the candidate. */








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        }
        /* Check to see if pWLoop should be added to the set of
        ** mxChoice best-so-far paths.
        **
        ** First look for an existing path among best-so-far paths
        ** that covers the same set of loops and has the same isOrdered
        ** setting as the current path candidate.
        **
        ** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent
        ** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range
        ** of legal values for isOrdered, -1..64.
        */
        for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){
          if( pTo->maskLoop==maskNew
           && ((pTo->isOrdered^isOrdered)&0x80)==0
          ){
            testcase( jj==nTo-1 );
            break;
          }
        }
        if( jj>=nTo ){
          /* None of the existing best-so-far paths match the candidate. */
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