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Overview
Comment:Improvements to the min()/max() optimization so that it is able to use indexes where terms are constrained by IN operators.
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SHA3-256: b8ba2f17f938c03543a89dd29d6987163f7a4085a51de1aa14ea5504501c4f72
User & Date: drh 2020-07-14 23:58:04
References
2021-01-14
20:57
Improvements to the min/max optimization. Fix for a performance regression introduced at [b8ba2f17f938c035] reported by forum post 4050026ab8 (check-in: 249a71cc user: drh tags: trunk)
2021-01-13
15:23
Further enhancements to the min/max optimization of check-in b8ba2f17f938c035 to fix the performance regression identified by forum post 4050026ab8. (check-in: 188772a1 user: drh tags: minmax-opt-exp)
Context
2020-07-15
02:15
New test cases for decimal and ieee754. (check-in: 73d62f82 user: drh tags: trunk)
2020-07-14
23:58
Improvements to the min()/max() optimization so that it is able to use indexes where terms are constrained by IN operators. (check-in: b8ba2f17 user: drh tags: trunk)
22:20
Now appears to work. All legacy tests pass. Need to add new tests, however. (Closed-Leaf check-in: 81e64509 user: drh tags: minmax-opt-exp)
15:30
Fix an obsolete header comment on the sqlite3WhereIsOrdered() routine. (check-in: 5041f6a1 user: drh tags: trunk)
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/select.c.

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          sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO);
        }
        sqlite3VdbeAddOp2(v, OP_Count, iCsr, pAggInfo->aFunc[0].iMem);
        sqlite3VdbeAddOp1(v, OP_Close, iCsr);
        explainSimpleCount(pParse, pTab, pBest);
      }else{
        int regAcc = 0;           /* "populate accumulators" flag */


        /* If there are accumulator registers but no min() or max() functions
        ** without FILTER clauses, allocate register regAcc. Register regAcc
        ** will contain 0 the first time the inner loop runs, and 1 thereafter.
        ** The code generated by updateAccumulator() uses this to ensure
        ** that the accumulator registers are (a) updated only once if
        ** there are no min() or max functions or (b) always updated for the








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          sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO);
        }
        sqlite3VdbeAddOp2(v, OP_Count, iCsr, pAggInfo->aFunc[0].iMem);
        sqlite3VdbeAddOp1(v, OP_Close, iCsr);
        explainSimpleCount(pParse, pTab, pBest);
      }else{
        int regAcc = 0;           /* "populate accumulators" flag */
        int addrSkip;

        /* If there are accumulator registers but no min() or max() functions
        ** without FILTER clauses, allocate register regAcc. Register regAcc
        ** will contain 0 the first time the inner loop runs, and 1 thereafter.
        ** The code generated by updateAccumulator() uses this to ensure
        ** that the accumulator registers are (a) updated only once if
        ** there are no min() or max functions or (b) always updated for the
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        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMaxOrderBy,
                                   0, minMaxFlag, 0);
        if( pWInfo==0 ){
          goto select_end;
        }
        updateAccumulator(pParse, regAcc, pAggInfo);
        if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
        if( sqlite3WhereIsOrdered(pWInfo)>0 ){

          sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo));
          VdbeComment((v, "%s() by index",
                (minMaxFlag==WHERE_ORDERBY_MIN?"min":"max")));
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, pAggInfo);
      }

      sSort.pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);








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        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMaxOrderBy,
                                   0, minMaxFlag, 0);
        if( pWInfo==0 ){
          goto select_end;
        }
        updateAccumulator(pParse, regAcc, pAggInfo);
        if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
        addrSkip = sqlite3WhereOrderByLimitOptLabel(pWInfo);
        if( addrSkip!=sqlite3WhereContinueLabel(pWInfo) ){
          sqlite3VdbeGoto(v, addrSkip);


        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, pAggInfo);
      }

      sSort.pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
︙︙

Changes to src/where.c.

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  testcase( nOrderBy==BMS-1 );
  if( nOrderBy>BMS-1 ) return 0;  /* Cannot optimize overly large ORDER BYs */
  isOrderDistinct = 1;
  obDone = MASKBIT(nOrderBy)-1;
  orderDistinctMask = 0;
  ready = 0;
  eqOpMask = WO_EQ | WO_IS | WO_ISNULL;

  if( wctrlFlags & WHERE_ORDERBY_LIMIT ) eqOpMask |= WO_IN;

  for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){
    if( iLoop>0 ) ready |= pLoop->maskSelf;
    if( iLoop<nLoop ){
      pLoop = pPath->aLoop[iLoop];
      if( wctrlFlags & WHERE_ORDERBY_LIMIT ) continue;
    }else{
      pLoop = pLast;








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  testcase( nOrderBy==BMS-1 );
  if( nOrderBy>BMS-1 ) return 0;  /* Cannot optimize overly large ORDER BYs */
  isOrderDistinct = 1;
  obDone = MASKBIT(nOrderBy)-1;
  orderDistinctMask = 0;
  ready = 0;
  eqOpMask = WO_EQ | WO_IS | WO_ISNULL;
  if( wctrlFlags & (WHERE_ORDERBY_LIMIT|WHERE_ORDERBY_MAX|WHERE_ORDERBY_MIN) ){
    eqOpMask |= WO_IN;
  }
  for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){
    if( iLoop>0 ) ready |= pLoop->maskSelf;
    if( iLoop<nLoop ){
      pLoop = pPath->aLoop[iLoop];
      if( wctrlFlags & WHERE_ORDERBY_LIMIT ) continue;
    }else{
      pLoop = pLast;
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      pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
                       ~ready, eqOpMask, 0);
      if( pTerm==0 ) continue;
      if( pTerm->eOperator==WO_IN ){
        /* IN terms are only valid for sorting in the ORDER BY LIMIT 
        ** optimization, and then only if they are actually used
        ** by the query plan */
        assert( wctrlFlags & WHERE_ORDERBY_LIMIT );

        for(j=0; j<pLoop->nLTerm && pTerm!=pLoop->aLTerm[j]; j++){}
        if( j>=pLoop->nLTerm ) continue;
      }
      if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
        Parse *pParse = pWInfo->pParse;
        CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pOrderBy->a[i].pExpr);
        CollSeq *pColl2 = sqlite3ExprCompareCollSeq(pParse, pTerm->pExpr);








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      pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
                       ~ready, eqOpMask, 0);
      if( pTerm==0 ) continue;
      if( pTerm->eOperator==WO_IN ){
        /* IN terms are only valid for sorting in the ORDER BY LIMIT 
        ** optimization, and then only if they are actually used
        ** by the query plan */
        assert( wctrlFlags & 
               (WHERE_ORDERBY_LIMIT|WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX) );
        for(j=0; j<pLoop->nLTerm && pTerm!=pLoop->aLTerm[j]; j++){}
        if( j>=pLoop->nLTerm ) continue;
      }
      if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
        Parse *pParse = pWInfo->pParse;
        CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pOrderBy->a[i].pExpr);
        CollSeq *pColl2 = sqlite3ExprCompareCollSeq(pParse, pTerm->pExpr);
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            testcase( wsFlags & WHERE_COLUMN_IN );
            if( rc==pWInfo->pOrderBy->nExpr ){
              pWInfo->bOrderedInnerLoop = 1;
              pWInfo->revMask = m;
            }
          }
        }





      }
    }
    if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP)
        && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0
    ){
      Bitmask revMask = 0;
      int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, 








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            testcase( wsFlags & WHERE_COLUMN_IN );
            if( rc==pWInfo->pOrderBy->nExpr ){
              pWInfo->bOrderedInnerLoop = 1;
              pWInfo->revMask = m;
            }
          }
        }
      }else if( nLoop
            && pWInfo->nOBSat==1
            && (pWInfo->wctrlFlags & (WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX))!=0
            ){
        pWInfo->bOrderedInnerLoop = 1;
      }
    }
    if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP)
        && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0
    ){
      Bitmask revMask = 0;
      int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy,
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