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For the OR-optimization, avoid generating OP_OpenRead opcodes that reopen

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exactly the same index.

FossilOrigin-Name: b67a6e33f23ce5f5d9a545fa9d6700a7ed636901
This commit is contained in:
drh
2014-07-22 00:40:45 +00:00
parent 215c0c82fa
commit 53ad7e48ab
4 changed files with 26 additions and 10 deletions
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19
src/where.c
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@@ -3422,6 +3422,7 @@ static Bitmask codeOneLoopStart(
int iRetInit; /* Address of regReturn init */
int untestedTerms = 0; /* Some terms not completely tested */
int ii; /* Loop counter */
int subWctrlFlags; /* wctrlFlags for sub-queries */
Expr *pAndExpr = 0; /* An ".. AND (...)" expression */
Table *pTab = pTabItem->pTab;
@@ -3517,6 +3518,8 @@ static Bitmask codeOneLoopStart(
** eliminating duplicates from other WHERE clauses, the action for each
** sub-WHERE clause is to to invoke the main loop body as a subroutine.
*/
subWctrlFlags = WHERE_OMIT_OPEN_CLOSE | WHERE_AND_ONLY |
WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY;
for(ii=0; ii<pOrWc->nTerm; ii++){
WhereTerm *pOrTerm = &pOrWc->a[ii];
if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){
@@ -3529,8 +3532,7 @@ static Bitmask codeOneLoopStart(
}
/* Loop through table entries that match term pOrTerm. */
pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
WHERE_OMIT_OPEN_CLOSE | WHERE_AND_ONLY |
WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY, iCovCur);
subWctrlFlags, iCovCur);
assert( pSubWInfo || pParse->nErr || db->mallocFailed );
if( pSubWInfo ){
WhereLoop *pSubLoop;
@@ -3621,6 +3623,7 @@ static Bitmask codeOneLoopStart(
){
assert( pSubWInfo->a[0].iIdxCur==iCovCur );
pCov = pSubLoop->u.btree.pIndex;
subWctrlFlags |= WHERE_OR_INDEX_OPEN;
}else{
pCov = 0;
}
@@ -6212,6 +6215,18 @@ WhereInfo *sqlite3WhereBegin(
pWInfo->aiCurOnePass[1] = iIndexCur;
}else if( iIdxCur && (wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ){
iIndexCur = iIdxCur;
if( (wctrlFlags & WHERE_OR_INDEX_OPEN)!=0 ){
/* For 2nd and subsequent subqueries for processing OR terms,
** try to reuse the previous OP_OpenRead, if there is one. The
** WHERE_OR_INDEX_OPEN bit will only be set if there is a prior
** OP_OpenRead opcode on cursor iIndexCur, so the while() loop
** below is guaranteed to terminate.
*/
VdbeOp *pOp = sqlite3VdbeGetOp(v, -1);
while( pOp->opcode!=OP_OpenRead || pOp->p1!=iIndexCur ) pOp--;
assert( pOp->p3==iDb );
if( pOp->p2==pIx->tnum ) op = 0;
}
}else{
iIndexCur = pParse->nTab++;
}