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Tweaks to the index selection logic.

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FossilOrigin-Name: 52d52688644f635a50a60ff17b160f3affa8fa6c
This commit is contained in:
drh
2013-09-11 03:53:22 +00:00
parent 36fabb6297
commit abfa6d52ed
5 changed files with 22 additions and 17 deletions
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16
src/where.c
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@@ -2557,6 +2557,7 @@ static int whereRangeScanEst(
){
int rc = SQLITE_OK;
int nOut = (int)*pnOut;
WhereCost nNew;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
Index *p = pBuilder->pNew->u.btree.pIndex;
@@ -2619,6 +2620,7 @@ static int whereRangeScanEst(
whereKeyStats(pParse, p, pRec, 0, a);
iNew = a[0] + ((pLower->eOperator & WO_GT) ? a[1] : 0);
if( iNew>iLower ) iLower = iNew;
nOut--;
}
}
@@ -2633,12 +2635,12 @@ static int whereRangeScanEst(
whereKeyStats(pParse, p, pRec, 1, a);
iNew = a[0] + ((pUpper->eOperator & WO_LE) ? a[1] : 0);
if( iNew<iUpper ) iUpper = iNew;
nOut--;
}
}
pBuilder->pRec = pRec;
if( rc==SQLITE_OK ){
WhereCost nNew;
if( iUpper>iLower ){
nNew = whereCost(iUpper - iLower);
}else{
@@ -2660,13 +2662,17 @@ static int whereRangeScanEst(
assert( pLower || pUpper );
/* TUNING: Each inequality constraint reduces the search space 4-fold.
** A BETWEEN operator, therefore, reduces the search space 16-fold */
nNew = nOut;
if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ){
nOut -= 20; assert( 20==whereCost(4) );
nNew -= 20; assert( 20==whereCost(4) );
nOut--;
}
if( pUpper ){
nOut -= 20; assert( 20==whereCost(4) );
nNew -= 20; assert( 20==whereCost(4) );
nOut--;
}
if( nOut<10 ) nOut = 10;
if( nNew<10 ) nNew = 10;
if( nNew<nOut ) nOut = nNew;
*pnOut = (WhereCost)nOut;
return rc;
}
@@ -4203,7 +4209,7 @@ static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
&& p->nLTerm<pTemplate->nLTerm
&& (p->wsFlags & pTemplate->wsFlags & WHERE_INDEXED)!=0
&& (p->u.btree.pIndex==pTemplate->u.btree.pIndex
|| p->u.btree.pIndex->nColumn>=pTemplate->u.btree.pIndex->nColumn)
|| pTemplate->rRun+p->nLTerm<=p->rRun+pTemplate->nLTerm)
){
/* Overwrite an existing WhereLoop with an similar one that uses
** more terms of the index */