Query optimizer enhancement: In "FROM a,b,c left join d" allow the C table
to be reordered with A and B. This used to be the case but the capability
was removed by (3203) and (3052) in response to ticket #1652. This change
restores the capability. (CVS 3529)
FossilOrigin-Name: 7393c81b8cb9d4344ae744de9eabcb3af64f1db8
diff --git a/src/expr.c b/src/expr.c
index 2ea27f5..1d5e186 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 1.269 2006/11/23 11:59:13 drh Exp $
+** $Id: expr.c,v 1.270 2006/12/16 16:25:15 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -891,22 +891,23 @@
pExpr->iColumn = j==pTab->iPKey ? -1 : j;
pExpr->affinity = pTab->aCol[j].affinity;
pExpr->pColl = sqlite3FindCollSeq(db, ENC(db), zColl,-1, 0);
- if( pItem->jointype & JT_NATURAL ){
- /* If this match occurred in the left table of a natural join,
- ** then skip the right table to avoid a duplicate match */
- pItem++;
- i++;
- }
- if( (pUsing = pItem->pUsing)!=0 ){
- /* If this match occurs on a column that is in the USING clause
- ** of a join, skip the search of the right table of the join
- ** to avoid a duplicate match there. */
- int k;
- for(k=0; k<pUsing->nId; k++){
- if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){
- pItem++;
- i++;
- break;
+ if( i<pSrcList->nSrc-1 ){
+ if( pItem[1].jointype & JT_NATURAL ){
+ /* If this match occurred in the left table of a natural join,
+ ** then skip the right table to avoid a duplicate match */
+ pItem++;
+ i++;
+ }else if( (pUsing = pItem[1].pUsing)!=0 ){
+ /* If this match occurs on a column that is in the USING clause
+ ** of a join, skip the search of the right table of the join
+ ** to avoid a duplicate match there. */
+ int k;
+ for(k=0; k<pUsing->nId; k++){
+ if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){
+ pItem++;
+ i++;
+ break;
+ }
}
}
}