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Multi-index OR-clause optimization now works for simple tests. There are

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no test scripts for it yet, though.  And it is disabled by default, pending
further testing and optimization.  We need a lot of both. (CVS 6058)

FossilOrigin-Name: d77a702358deddfa9987147999d06a235e730fa9
This commit is contained in:
drh
2008-12-23 13:35:23 +00:00
parent 1f58153a9a
commit dd5f5a6231
5 changed files with 79 additions and 31 deletions
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82
src/where.c
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@@ -16,7 +16,7 @@
** so is applicable. Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.340 2008/12/21 03:51:16 drh Exp $
** $Id: where.c,v 1.341 2008/12/23 13:35:23 drh Exp $
*/
#include "sqliteInt.h"
@@ -142,7 +142,6 @@ struct WhereClause {
struct WhereOrInfo {
WhereClause wc; /* Decomposition into subterms */
Bitmask indexable; /* Bitmask of all indexable tables in the clause */
WherePlan *aPlan; /* Search plan for each subterm */
};
/*
@@ -268,7 +267,6 @@ static void whereClauseClear(WhereClause*);
static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
if( p ){
whereClauseClear(&p->wc);
sqlite3DbFree(db, p->aPlan);
sqlite3DbFree(db, p);
}
}
@@ -826,7 +824,6 @@ static void exprAnalyzeOrTerm(
pTerm->wtFlags |= TERM_ORINFO;
pOrWc = &pOrInfo->wc;
whereClauseInit(pOrWc, pWC->pParse, pMaskSet);
pOrInfo->aPlan = 0;
whereSplit(pOrWc, pExpr, TK_OR);
exprAnalyzeAll(pSrc, pOrWc);
if( db->mallocFailed ) return;
@@ -962,12 +959,6 @@ static void exprAnalyzeOrTerm(
pTerm->eOperator = 0; /* case 1 trumps case 2 */
}
}
/* If case 2 applies, allocate space for pOrInfo->aPlan
*/
if( pTerm->eOperator==WO_OR ){
pOrInfo->aPlan = sqlite3DbMallocRaw(db, pOrWc->nTerm*sizeof(WherePlan));
}
}
#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
@@ -1723,6 +1714,8 @@ static void bestIndex(
int eqTermMask; /* Mask of valid equality operators */
double cost; /* Cost of using pProbe */
double nRow; /* Estimated number of rows in result set */
int i; /* Loop counter */
Bitmask maskSrc; /* Bitmask for the pSrc table */
WHERETRACE(("bestIndex: tbl=%s notReady=%llx\n", pSrc->pTab->zName,notReady));
pProbe = pSrc->pTab->pIndex;
@@ -1821,6 +1814,44 @@ static void bestIndex(
}
}
#if SQLITE_ENABLE_MULTI_OR
/* Search for an OR-clause that can be used to look up the table.
*/
maskSrc = getMask(pWC->pMaskSet, iCur);
for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
WhereClause tempWC;
tempWC = *pWC;
tempWC.nSlot = 1;
if( pTerm->eOperator==WO_OR
&& ((pTerm->prereqAll & ~maskSrc) & notReady)==0
&& (pTerm->u.pOrInfo->indexable & maskSrc)!=0 ){
WhereClause *pOrWC = &pTerm->u.pOrInfo->wc;
WhereTerm *pOrTerm;
int j;
double rTotal = 0;
double nRow = 0;
for(j=0, pOrTerm=pOrWC->a; j<pOrWC->nTerm; j++, pOrTerm++){
WhereCost sTermCost;
if( pOrTerm->leftCursor!=iCur ) continue;
tempWC.a = pOrTerm;
bestIndex(pParse, &tempWC, pSrc, notReady, 0, &sTermCost);
if( sTermCost.plan.wsFlags==0 ){
rTotal = pCost->rCost;
break;
}
rTotal += sTermCost.rCost;
nRow += sTermCost.nRow;
}
if( rTotal<pCost->rCost ){
pCost->rCost = rTotal;
pCost->nRow = nRow;
pCost->plan.wsFlags = WHERE_MULTI_OR;
pCost->plan.u.pTerm = pTerm;
}
}
}
#endif
/* If the pSrc table is the right table of a LEFT JOIN then we may not
** use an index to satisfy IS NULL constraints on that table. This is
** because columns might end up being NULL if the table does not match -
@@ -2529,7 +2560,10 @@ static Bitmask codeOneLoopStart(
pLevel->p1 = iIdxCur;
disableTerm(pLevel, pRangeStart);
disableTerm(pLevel, pRangeEnd);
}else if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
}else
#if SQLITE_ENABLE_MULTI_OR
if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
/* Case 4: Two or more separately indexed terms connected by OR
**
** Example:
@@ -2562,6 +2596,7 @@ static Bitmask codeOneLoopStart(
WhereTerm *pTerm; /* The complete OR-clause */
WhereClause *pOrWc; /* The OR-clause broken out into subterms */
WhereTerm *pOrTerm; /* A single subterm within the OR-clause */
SrcList oneTab; /* Shortened table list */
pTerm = pLevel->plan.u.pTerm;
assert( pTerm!=0 );
@@ -2570,12 +2605,22 @@ static Bitmask codeOneLoopStart(
pOrWc = &pTerm->u.pOrInfo->wc;
regRowset = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp1(v, OP_Null, regRowset);
for(j=0, pOrTerm=pOrWc->a; j<pOrWc->nTerm; j++, pOrTerm++){
if( pOrTerm->leftCursor!=iCur ) continue;
/* fillRowSetFromIdx(pParse, regRowset, pTabItem, pOrTerm); */
}
regNextRowid = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
oneTab.nSrc = 1;
oneTab.nAlloc = 1;
oneTab.a[0] = *pTabItem;
for(j=0, pOrTerm=pOrWc->a; j<pOrWc->nTerm; j++, pOrTerm++){
WhereInfo *pSubWInfo;
if( pOrTerm->leftCursor!=iCur ) continue;
pSubWInfo = sqlite3WhereBegin(pParse, &oneTab, pOrTerm->pExpr, 0, 0);
if( pSubWInfo ){
sqlite3VdbeAddOp2(v, OP_Rowid, oneTab.a[0].iCursor, regNextRowid);
sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowset, regNextRowid);
pSubWInfo->a[0].plan.wsFlags |= WHERE_IDX_ONLY;
sqlite3WhereEnd(pSubWInfo);
}
}
sqlite3VdbeResolveLabel(v, addrCont);
addrCont =
sqlite3VdbeAddOp3(v, OP_RowSetRead, regRowset, addrBrk, regNextRowid);
@@ -2583,7 +2628,10 @@ static Bitmask codeOneLoopStart(
sqlite3ReleaseTempReg(pParse, regNextRowid);
pLevel->op = OP_Goto;
pLevel->p2 = addrCont;
}else{
}else
#endif /* SQLITE_ENABLE_MULTI_OR */
{
/* Case 5: There is no usable index. We must do a complete
** scan of the entire table.
*/