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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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23
src/where.c
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@@ -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.