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Add the SQLITE_ENABLE_EARLY_CURSOR_CLOSE compile-time option which causes

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read cursors to be closed after their usefulness ends during a two-pass
UPDATE.

FossilOrigin-Name: 7def6c8edd85f19ee09038e01541f75b1f71ca39b9fb782b8f0fcac89207c353
This commit is contained in:
drh
2019-01-17 19:33:16 +00:00
parent f66da6ce8e
commit aa0f2d0efa
3 changed files with 31 additions and 8 deletions
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23
src/where.c
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@@ -5262,6 +5262,29 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
continue;
}
#ifdef SQLITE_ENABLE_EARLY_CURSOR_CLOSE
/* Close all of the cursors that were opened by sqlite3WhereBegin.
** Except, do not close cursors that will be reused by the OR optimization
** (WHERE_OR_SUBCLAUSE). And do not close the OP_OpenWrite cursors
** created for the ONEPASS optimization.
*/
if( (pTab->tabFlags & TF_Ephemeral)==0
&& pTab->pSelect==0
&& (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0
){
int ws = pLoop->wsFlags;
if( pWInfo->eOnePass==ONEPASS_OFF && (ws & WHERE_IDX_ONLY)==0 ){
sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
}
if( (ws & WHERE_INDEXED)!=0
&& (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0
&& pLevel->iIdxCur!=pWInfo->aiCurOnePass[1]
){
sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
}
}
#endif
/* If this scan uses an index, make VDBE code substitutions to read data
** from the index instead of from the table where possible. In some cases
** this optimization prevents the table from ever being read, which can