From: Darren King

I have always been under the impression that NULL is not equal to
NULL and that NULL is not equal to anything else either.  If this
is the case, then this patch is correct.

If NULL _is_ equal to NULL, then I think there are other problems
in the Group By logic.

diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 15ba3ed94174efc95aab179e4eed002d20e562f5..196d347df43ef75eb1a28d1a34b78e1e4544c07a 100644 (file)
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -13,7 +13,7 @@
  *   columns. (ie. tuples from the same group are consecutive)
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/executor/nodeGroup.c,v 1.11 1997/10/27 12:00:43 vadim Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/executor/nodeGroup.c,v 1.12 1998/01/26 00:21:02 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -415,8 +415,11 @@ sameGroup(TupleTableSlot *oldslot,
 
        if (isNull1 == isNull2)
        {
-           if (isNull1)        /* both are null, they are equal */
-               continue;
+           /* both are null, they are _not_ equal since
+            * NULL is not equal to NULL (or anything).
+            *   --  25 Jan 1998  --  darrenk */
+           if (isNull1)
+               return FALSE;
 
            val1 = fmgr(typoutput, attr1,
                        gettypelem(tupdesc->attrs[att - 1]->atttypid));