We have to return dummy tuple for empty targetlist!

Try select t1.x from t1, t2 where t1.y = 1 and t2.y = 1
- t2 scan target list will be empty and so no one tuple
will be returned...

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index b1d29f3d8e563b8ee0433eeff8b7434df497146a..87eeb835686d1d8d11740ff80c56a9bf1ca5220a 100644 (file)
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.46 1999/02/23 07:33:44 thomas Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.47 1999/03/10 12:16:09 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1474,10 +1474,15 @@ ExecTargetList(List *targetlist,
         *      is this a new phenomenon? it might cause bogus behavior
         *      if we try to free this tuple later!! I put a hook in
         *      ExecProject to watch out for this case -mer 24 Aug 1992
+        *
+        *      We must return dummy tuple!!! Try 
+        *      select t1.x from t1, t2 where t1.y = 1 and t2.y = 1
+        *      - t2 scan target list will be empty and so no one tuple
+        *      will be returned! But Mer was right - dummy tuple
+        *      must be palloced... - vadim 03/01/1999
         */
-       CXT1_printf("ExecTargetList: context is %d\n", CurrentMemoryContext);
        *isDone = true;
-       return (HeapTuple) true;
+       return (HeapTuple) palloc(1);
    }
 
    /*
@@ -1640,12 +1645,6 @@ ExecProject(ProjectionInfo *projInfo, bool *isDone)
    tupValue = projInfo->pi_tupValue;
    econtext = projInfo->pi_exprContext;
 
-   if (targetlist == NIL)
-   {
-       *isDone = true;
-       return (TupleTableSlot *) NULL;
-   }
-
    /*
     *  form a new (result) tuple
     */