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Run as many Bloom filters as possible before index lookups.

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FossilOrigin-Name: 06f6fefd67086896bc49272c6319545ff6c6792f18babe23aced27b60b032119
This commit is contained in:
drh
2021-12-05 20:19:47 +00:00
parent 35685d3e5e
commit 6ae49e67cc
6 changed files with 158 additions and 76 deletions
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77
src/wherecode.c
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@@ -196,9 +196,6 @@ int sqlite3WhereExplainOneScan(
pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr);
}
#endif
if( flags & WHERE_BLOOMFILTER ){
sqlite3_str_appendf(&str, " WITH BLOOM FILTER");
}
#ifdef SQLITE_EXPLAIN_ESTIMATED_ROWS
if( pLoop->nOut>=10 ){
sqlite3_str_appendf(&str, " (~%llu rows)",
@@ -214,6 +211,52 @@ int sqlite3WhereExplainOneScan(
}
return ret;
}
/*
** Add a single OP_Explain opcode that describes a Bloom filter.
**
** Or if not processing EXPLAIN QUERY PLAN and not in a SQLITE_DEBUG and/or
** SQLITE_ENABLE_STMT_SCANSTATUS build, then OP_Explain opcodes are not
** required and this routine is a no-op.
**
** If an OP_Explain opcode is added to the VM, its address is returned.
** Otherwise, if no OP_Explain is coded, zero is returned.
*/
int sqlite3WhereExplainBloomFilter(
const Parse *pParse, /* Parse context */
const WhereInfo *pWInfo, /* WHERE clause */
const WhereLevel *pLevel /* Bloom filter on this level */
){
int ret = 0;
#if !defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_STMT_SCANSTATUS)
if( sqlite3ParseToplevel(pParse)->explain==2 )
#endif
{
SrcItem *pItem = &pWInfo->pTabList->a[pLevel->iFrom];
Vdbe *v = pParse->pVdbe; /* VM being constructed */
sqlite3 *db = pParse->db; /* Database handle */
char *zMsg; /* Text to add to EQP output */
int i; /* Loop counter */
WhereLoop *pLoop; /* The where loop */
StrAccum str; /* EQP output string */
char zBuf[100]; /* Initial space for EQP output string */
sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
str.printfFlags = SQLITE_PRINTF_INTERNAL;
sqlite3_str_appendf(&str, "BLOOM FILTER ON %S(", pItem);
pLoop = pLevel->pWLoop;
for(i=pLoop->nSkip; i<pLoop->u.btree.nEq; i++){
const char *z = pItem->pTab->aCol[i].zCnName;
if( i>pLoop->nSkip ) sqlite3_str_append(&str, " AND ", 5);
sqlite3_str_appendf(&str, "%s=?", z);
}
sqlite3_str_append(&str, ")", 1);
zMsg = sqlite3StrAccumFinish(&str);
ret = sqlite3VdbeAddOp4(v, OP_Explain, sqlite3VdbeCurrentAddr(v),
pParse->addrExplain, 0, zMsg,P4_DYNAMIC);
}
return ret;
}
#endif /* SQLITE_OMIT_EXPLAIN */
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
@@ -1304,14 +1347,20 @@ static void whereApplyPartialIndexConstraints(
}
}
#if 1
/*
** An OP_Filter has just been generated, but the corresponding
** index search has not yet been performed. This routine
** checks to see if there are additional WHERE_BLOOMFILTER in
** inner loops that can be evaluated right away, and if there are,
** it evaluates those filters as well, and removes the WHERE_BLOOMFILTER
** tag.
** This routine is called right after An OP_Filter has been generated and
** before the corresponding index search has been performed. This routine
** checks to see if there are additional Bloom filters in inner loops that
** can be checked prior to doing the index lookup. If there are available
** inner-loop Bloom filters, then evaluate those filters now, before the
** index lookup. The idea is that a Bloom filter check is way faster than
** an index lookup, and the Bloom filter might return false, meaning that
** the index lookup can be skipped.
**
** We know that an inner loop uses a Bloom filter because it has the
** WhereLevel.regFilter set. If an inner-loop Bloom filter is checked,
** then clear the WhereLoeve.regFilter value to prevent the Bloom filter
** from being checked a second time when the inner loop is evaluated.
*/
static SQLITE_NOINLINE void filterPullDown(
Parse *pParse, /* Parsing context */
@@ -1323,9 +1372,8 @@ static SQLITE_NOINLINE void filterPullDown(
while( ++iLevel < pWInfo->nLevel ){
WhereLevel *pLevel = &pWInfo->a[iLevel];
WhereLoop *pLoop = pLevel->pWLoop;
if( (pLoop->wsFlags & WHERE_BLOOMFILTER)==0 ) continue;
if( pLevel->regFilter==0 ) continue;
if( pLoop->prereq & notReady ) continue;
sqlite3ConstructBloomFilter(pWInfo, &pWInfo->a[iLevel]);
if( pLoop->wsFlags & WHERE_IPK ){
WhereTerm *pTerm = pLoop->aLTerm[0];
int r1, regRowid;
@@ -1351,12 +1399,9 @@ static SQLITE_NOINLINE void filterPullDown(
addrNxt, r1, nEq);
VdbeCoverage(pParse->pVdbe);
}
pLoop->wsFlags &= ~WHERE_BLOOMFILTER;
pLevel->regFilter = 0;
}
}
#else
#define filterPullDown(A,B,C,D,E)
#endif
/*
** Generate code for the start of the iLevel-th loop in the WHERE clause