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Overview
Comment:Further enhancements to the min/max optimization of check-in b8ba2f17f938c035 to fix the performance regression identified by forum post 4050026ab8.
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SHA3-256: 188772a1dbaf066fbddd39c718fdd87478b19a920622f4640bcb79d4ef065331
User & Date: drh 2021-01-13 15:23:17
Original Comment: Further enhancements to the min/max optimization of check-in b8ba2f17f938c035 to fix the performance regression identified by forum post 623f571482.
Context
2021-01-13
19:28
Expand the number of optimization-disable bits from 16 to 32. Use one of the new bits to disable the min/max optimization, so that we can more easily verify that we get the same answer both with and within that optimization. (check-in: fd0c9a12 user: drh tags: minmax-opt-exp)
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)
12:59
cli: Omit surplus whitespace at the end of lines in .explain output. (check-in: 11e4eb09 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/select.c.
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      updateAccumulator(pParse, iUseFlag, pAggInfo);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
      VdbeComment((v, "indicate data in accumulator"));

      /* End of the loop
      */
      if( groupBySort ){
        sqlite3VdbeAddOp2(v, OP_SorterNext, pAggInfo->sortingIdx, addrTopOfLoop);
        VdbeCoverage(v);
      }else{
        sqlite3WhereEnd(pWInfo);
        sqlite3VdbeChangeToNoop(v, addrSortingIdx);
      }

      /* Output the final row of result







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      updateAccumulator(pParse, iUseFlag, pAggInfo);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
      VdbeComment((v, "indicate data in accumulator"));

      /* End of the loop
      */
      if( groupBySort ){
        sqlite3VdbeAddOp2(v, OP_SorterNext, pAggInfo->sortingIdx,addrTopOfLoop);
        VdbeCoverage(v);
      }else{
        sqlite3WhereEnd(pWInfo);
        sqlite3VdbeChangeToNoop(v, addrSortingIdx);
      }

      /* Output the final row of result
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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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          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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        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);







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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( minMaxFlag ){
          sqlite3WhereMinMaxOptEarlyOut(v, pWInfo);

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

      sSort.pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
Changes to src/sqliteInt.h.
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                   Upsert*);
WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,ExprList*,u16,int);
void sqlite3WhereEnd(WhereInfo*);
LogEst sqlite3WhereOutputRowCount(WhereInfo*);
int sqlite3WhereIsDistinct(WhereInfo*);
int sqlite3WhereIsOrdered(WhereInfo*);
int sqlite3WhereOrderByLimitOptLabel(WhereInfo*);

int sqlite3WhereIsSorted(WhereInfo*);
int sqlite3WhereContinueLabel(WhereInfo*);
int sqlite3WhereBreakLabel(WhereInfo*);
int sqlite3WhereOkOnePass(WhereInfo*, int*);
#define ONEPASS_OFF      0        /* Use of ONEPASS not allowed */
#define ONEPASS_SINGLE   1        /* ONEPASS valid for a single row update */
#define ONEPASS_MULTI    2        /* ONEPASS is valid for multiple rows */







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                   Upsert*);
WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,ExprList*,u16,int);
void sqlite3WhereEnd(WhereInfo*);
LogEst sqlite3WhereOutputRowCount(WhereInfo*);
int sqlite3WhereIsDistinct(WhereInfo*);
int sqlite3WhereIsOrdered(WhereInfo*);
int sqlite3WhereOrderByLimitOptLabel(WhereInfo*);
void sqlite3WhereMinMaxOptEarlyOut(Vdbe*,WhereInfo*);
int sqlite3WhereIsSorted(WhereInfo*);
int sqlite3WhereContinueLabel(WhereInfo*);
int sqlite3WhereBreakLabel(WhereInfo*);
int sqlite3WhereOkOnePass(WhereInfo*, int*);
#define ONEPASS_OFF      0        /* Use of ONEPASS not allowed */
#define ONEPASS_SINGLE   1        /* ONEPASS valid for a single row update */
#define ONEPASS_MULTI    2        /* ONEPASS is valid for multiple rows */
Changes to src/where.c.
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    ** continuation of the inner-most loop. */
    return pWInfo->iContinue;
  }
  pInner = &pWInfo->a[pWInfo->nLevel-1];
  assert( pInner->addrNxt!=0 );
  return pInner->addrNxt;
}
























/*
** Return the VDBE address or label to jump to in order to continue
** immediately with the next row of a WHERE clause.
*/
int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
  assert( pWInfo->iContinue!=0 );







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    ** continuation of the inner-most loop. */
    return pWInfo->iContinue;
  }
  pInner = &pWInfo->a[pWInfo->nLevel-1];
  assert( pInner->addrNxt!=0 );
  return pInner->addrNxt;
}

/*
** While generating code for the min/max optimization, after handling
** the aggregate-step call to min() or max(), check to see if any
** additional looping is required.  If the output order is such that
** we are certain that the correct answer has already been found, then
** code an OP_Goto to by pass subsequent processing.
**
** Any extra OP_Goto that is coded here is an optimization.  The
** correct answer should be obtained regardless.  This OP_Goto just
** makes the answer appear faster.
*/
void sqlite3WhereMinMaxOptEarlyOut(Vdbe *v, WhereInfo *pWInfo){
  WhereLevel *pInner;
  if( !pWInfo->bOrderedInnerLoop ) return;
  if( pWInfo->nOBSat==0 ) return;
  pInner = &pWInfo->a[pWInfo->nLevel-1];
  if( (pInner->pWLoop->wsFlags & WHERE_COLUMN_IN)==0 ){
    sqlite3VdbeGoto(v, pWInfo->iBreak);
  }else if( pInner->addrNxt!=pWInfo->iContinue ){
    sqlite3VdbeGoto(v, pInner->addrNxt);
  }
}

/*
** Return the VDBE address or label to jump to in order to continue
** immediately with the next row of a WHERE clause.
*/
int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
  assert( pWInfo->iContinue!=0 );