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Further enhancements to the min/max optimization of

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[/info/b8ba2f17f938c035|check-in b8ba2f17f938c035] to fix the performance
regression identified by
[forum:/forumpost/623f571482|forum post 623f571482].

FossilOrigin-Name: 188772a1dbaf066fbddd39c718fdd87478b19a920622f4640bcb79d4ef065331
This commit is contained in:
drh
2021-01-13 15:23:17 +00:00
parent aa556b0fa7
commit d193057ad1
5 changed files with 39 additions and 14 deletions
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8
src/select.c
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@@ -6773,7 +6773,7 @@ int sqlite3Select(
/* End of the loop
*/
if( groupBySort ){
sqlite3VdbeAddOp2(v, OP_SorterNext, pAggInfo->sortingIdx, addrTopOfLoop);
sqlite3VdbeAddOp2(v, OP_SorterNext, pAggInfo->sortingIdx,addrTopOfLoop);
VdbeCoverage(v);
}else{
sqlite3WhereEnd(pWInfo);
@@ -6885,7 +6885,6 @@ int sqlite3Select(
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
@@ -6934,9 +6933,8 @@ int sqlite3Select(
}
updateAccumulator(pParse, regAcc, pAggInfo);
if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
addrSkip = sqlite3WhereOrderByLimitOptLabel(pWInfo);
if( addrSkip!=sqlite3WhereContinueLabel(pWInfo) ){
sqlite3VdbeGoto(v, addrSkip);
if( minMaxFlag ){
sqlite3WhereMinMaxOptEarlyOut(v, pWInfo);
}
sqlite3WhereEnd(pWInfo);
finalizeAggFunctions(pParse, pAggInfo);

1
src/sqliteInt.h
View File

@@ -4341,6 +4341,7 @@ 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*);

23
src/where.c
View File

@@ -99,6 +99,29 @@ int sqlite3WhereOrderByLimitOptLabel(WhereInfo *pWInfo){
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.