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Improvements on the decision of whether or not to use a Bloom filter.

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FossilOrigin-Name: 0fb2a4e08f518cb38ea3edc6a084d1e4874fd622ba3cf9101b49b3e7dc1a3f2b
This commit is contained in:
drh
2021-12-08 19:50:45 +00:00
parent c491a25631
commit fb82caf0be
4 changed files with 33 additions and 19 deletions
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35
src/where.c
View File

@@ -2028,9 +2028,9 @@ void sqlite3WhereLoopPrint(WhereLoop *p, WhereClause *pWC){
sqlite3_free(z);
}
if( p->wsFlags & WHERE_SKIPSCAN ){
sqlite3DebugPrintf(" f %05x %d-%d", p->wsFlags, p->nLTerm,p->nSkip);
sqlite3DebugPrintf(" f %06x %d-%d", p->wsFlags, p->nLTerm,p->nSkip);
}else{
sqlite3DebugPrintf(" f %05x N %d", p->wsFlags, p->nLTerm);
sqlite3DebugPrintf(" f %06x N %d", p->wsFlags, p->nLTerm);
}
sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut);
if( p->nLTerm && (sqlite3WhereTrace & 0x100)!=0 ){
@@ -2502,6 +2502,9 @@ static void whereLoopOutputAdjust(
if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break;
}
if( j<0 ){
if( pLoop->maskSelf==pTerm->prereqAll ){
pLoop->wsFlags |= WHERE_CULLED;
}
if( pTerm->truthProb<=0 ){
/* If a truth probability is specified using the likelihood() hints,
** then use the probability provided by the application. */
@@ -2529,7 +2532,9 @@ static void whereLoopOutputAdjust(
}
}
}
if( pLoop->nOut > nRow-iReduce ) pLoop->nOut = nRow - iReduce;
if( pLoop->nOut > nRow-iReduce ){
pLoop->nOut = nRow - iReduce;
}
}
/*
@@ -4984,22 +4989,30 @@ static SQLITE_NOINLINE void whereCheckIfBloomFilterIsUseful(
){
int i;
LogEst nSearch;
SrcItem *pItem;
assert( pWInfo->nLevel>=2 );
assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_BloomFilter) );
nSearch = pWInfo->a[0].pWLoop->nOut;
for(i=1; i<pWInfo->nLevel; i++){
WhereLoop *pLoop = pWInfo->a[i].pWLoop;
if( pLoop->nOut<0
const int reqFlags = (WHERE_CULLED|WHERE_COLUMN_EQ);
if( (pLoop->wsFlags & reqFlags)==reqFlags
&& (pLoop->wsFlags & (WHERE_IPK|WHERE_INDEXED))!=0
&& (pLoop->wsFlags & WHERE_COLUMN_EQ)!=0
&& nSearch > (pItem = &pWInfo->pTabList->a[pLoop->iTab])->pTab->nRowLogEst
&& (pItem->fg.jointype & JT_LEFT)==0
){
pLoop->wsFlags |= WHERE_BLOOMFILTER;
pLoop->wsFlags &= ~WHERE_IDX_ONLY;
WHERETRACE(0xffff, ("-> use Bloom-filter on loop %c\n", pLoop->cId));
SrcItem *pItem = &pWInfo->pTabList->a[pLoop->iTab];
Table *pTab = pItem->pTab;
pTab->tabFlags |= TF_StatsUsed;
if( nSearch > pTab->nRowLogEst
&& (pItem->fg.jointype & JT_LEFT)==0
){
pLoop->wsFlags |= WHERE_BLOOMFILTER;
pLoop->wsFlags &= ~WHERE_IDX_ONLY;
WHERETRACE(0xffff, (
"-> use Bloom-filter on loop %c because there are ~%.1e "
"lookups into %s which has only ~%.1e rows\n",
pLoop->cId, (double)sqlite3LogEstToInt(nSearch), pTab->zName,
(double)sqlite3LogEstToInt(pTab->nRowLogEst)));
}
}
nSearch += pLoop->nOut;
}

1
src/whereInt.h
View File

@@ -608,5 +608,6 @@ void sqlite3WhereTabFuncArgs(Parse*, SrcItem*, WhereClause*);
#define WHERE_IN_SEEKSCAN 0x00100000 /* Seek-scan optimization for IN */
#define WHERE_TRANSCONS 0x00200000 /* Uses a transitive constraint */
#define WHERE_BLOOMFILTER 0x00400000 /* Consider using a Bloom-filter */
#define WHERE_CULLED 0x00800000 /* nOut reduced by extra WHERE terms */
#endif /* !defined(SQLITE_WHEREINT_H) */