Candidate fix for ticket #3082. Test cases needed. (CVS 5047)
FossilOrigin-Name: f6313311ddfb1ee2d6660b9be99afe721a8a9aff
diff --git a/src/expr.c b/src/expr.c
index 1aab48b..9dfd6fc 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
-** $Id: expr.c,v 1.368 2008/04/24 12:36:35 danielk1977 Exp $
+** $Id: expr.c,v 1.369 2008/04/25 00:08:38 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1577,6 +1577,45 @@
#endif
/*
+** Return true if the IN operator optimization is enabled and
+** the SELECT statement p exists and is of the
+** simple form:
+**
+** SELECT <column> FROM <table>
+**
+** If this is the case, it may be possible to use an existing table
+** or index instead of generating an epheremal table.
+*/
+#ifndef SQLITE_OMIT_SUBQUERY
+static int isCandidateForInOpt(Select *p){
+ SrcList *pSrc;
+ ExprList *pEList;
+ Table *pTab;
+ if( !sqlite3_enable_in_opt ) return 0; /* IN optimization must be enabled */
+ if( p==0 ) return 0; /* right-hand side of IN is SELECT */
+ if( p->pPrior ) return 0; /* Not a compound SELECT */
+ if( p->isDistinct ) return 0; /* No DISTINCT keyword */
+ if( p->isAgg ) return 0; /* Contains no aggregate functions */
+ if( p->pGroupBy ) return 0; /* Has no GROUP BY clause */
+ if( p->pLimit ) return 0; /* Has no LIMIT clause */
+ if( p->pOffset ) return 0;
+ if( p->pWhere ) return 0; /* Has no WHERE clause */
+ pSrc = p->pSrc;
+ if( pSrc==0 ) return 0; /* A single table in the FROM clause */
+ if( pSrc->nSrc!=1 ) return 0;
+ if( pSrc->a[0].pSelect ) return 0; /* FROM clause is not a subquery */
+ pTab = pSrc->a[0].pTab;
+ if( pTab==0 ) return 0;
+ if( pTab->pSelect ) return 0; /* FROM clause is not a view */
+ if( IsVirtual(pTab) ) return 0; /* FROM clause not a virtual table */
+ pEList = p->pEList;
+ if( pEList->nExpr!=1 ) return 0; /* One column in the result set */
+ if( pEList->a[0].pExpr->op!=TK_COLUMN ) return 0; /* Result is a column */
+ return 1;
+}
+#endif /* SQLITE_OMIT_SUBQUERY */
+
+/*
** This function is used by the implementation of the IN (...) operator.
** It's job is to find or create a b-tree structure that may be used
** either to test for membership of the (...) set or to iterate through
@@ -1621,14 +1660,8 @@
** If this is the case, it may be possible to use an existing table
** or index instead of generating an epheremal table.
*/
- if( sqlite3_enable_in_opt
- && (p=pX->pSelect)!=0 && !p->pPrior
- && !p->isDistinct && !p->isAgg && !p->pGroupBy
- && p->pSrc && p->pSrc->nSrc==1 && !p->pSrc->a[0].pSelect
- && p->pSrc->a[0].pTab && !p->pSrc->a[0].pTab->pSelect
- && p->pEList->nExpr==1 && p->pEList->a[0].pExpr->op==TK_COLUMN
- && !p->pLimit && !p->pOffset && !p->pWhere
- ){
+ p = pX->pSelect;
+ if( isCandidateForInOpt(p) ){
sqlite3 *db = pParse->db;
Index *pIdx;
Expr *pExpr = p->pEList->a[0].pExpr;