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Add the OP_ReopenIdx opcode that works like OP_OpenRead except that it becomes

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a no-op if the cursor is already open on the same index.  Update the
OR-optimization logic to make use of OP_ReopenIdx in order to avoid
unnecessary cursor open requests sent to the B-Tree layer.

FossilOrigin-Name: 77f412caf0192d3e7fecb377d6d72123d8b64424
This commit is contained in:
drh
2014-07-22 20:02:19 +00:00
parent a45fdc7b1e
commit 3526319b48
6 changed files with 49 additions and 15 deletions
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8
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 */
u16 wctrlFlags; /* Flags for sub-WHERE clause */
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.
*/
wctrlFlags = 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);
wctrlFlags, 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;
wctrlFlags |= WHERE_REOPEN_IDX;
}else{
pCov = 0;
}
@@ -6219,6 +6222,7 @@ WhereInfo *sqlite3WhereBegin(
pWInfo->aiCurOnePass[1] = iIndexCur;
}else if( iIdxCur && (wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ){
iIndexCur = iIdxCur;
if( wctrlFlags & WHERE_REOPEN_IDX ) op = OP_ReopenIdx;
}else{
iIndexCur = pParse->nTab++;
}