Fix nodeAgg coredump in case where lower-level plan has

an empty targetlist *and* fails to return any tuples, as will happen
for example with 'SELECT COUNT(1) FROM table WHERE ...' if the where-
clause selects no tuples.  It's so nice to make a fix by diking out code,
instead of adding more...

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 9e4638ccab80cbc30ab75d622814e9ae6234eff4..c37f4c4f42f9c49d520f04525fbe9e8cb76c0b1b 100644 (file)
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -11,7 +11,7 @@
  *       SQL aggregates. (Do not expect POSTQUEL semantics.)    -- ay 2/95
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.55 1999/09/26 21:21:09 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.56 1999/09/28 02:03:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -373,7 +373,8 @@ ExecAgg(Agg *node)
                                elog(ERROR, "ExecAgg: no valid transition functions??");
 
                        /*
-                        * Release any per-group working storage.
+                        * Release any per-group working storage, unless we're passing
+                        * it back as the result of the aggregate.
                         */
                        if (OidIsValid(peraggstate->xfn1_oid) &&
                                ! peraggstate->value1IsNull &&
@@ -411,34 +412,20 @@ ExecAgg(Agg *node)
                        aggstate->agg_done = true;
 
                /*
-                * When the outerPlan doesn't return a single tuple,
-                * create a dummy input tuple anyway because we still need
-                * to return a valid aggregate tuple.  (XXX isn't this wasted
-                * effort?  Since we're not in GROUP BY mode, it shouldn't be
-                * possible for the projected result to refer to any raw input
-                * columns??)  The values returned for the aggregates will be
-                * the initial values of the transition functions.
+                * We used to create a dummy all-nulls input tuple here if
+                * inputTuple == NULL (ie, the outerPlan didn't return anything).
+                * However, now that we don't return a bogus tuple in Group mode,
+                * we can only get here with inputTuple == NULL in non-Group mode.
+                * So, if the parser has done its job right, the projected output
+                * tuple's targetList must not contain any direct references to
+                * input columns, and so it's a waste of time to create an
+                * all-nulls input tuple.  We just let the tuple slot get set
+                * to NULL instead.  The values returned for the aggregates will
+                * be the initial values of the transition functions.
                 */
-               if (inputTuple == NULL)
-               {
-                       TupleDesc       tupType;
-                       Datum      *tupValue;
-                       char       *null_array;
-                       AttrNumber      attnum;
-
-                       tupType = aggstate->csstate.css_ScanTupleSlot->ttc_tupleDescriptor;
-                       tupValue = projInfo->pi_tupValue;
-
-                       /* set all the values to NULL */
-                       null_array = palloc(sizeof(char) * tupType->natts);
-                       for (attnum = 0; attnum < tupType->natts; attnum++)
-                               null_array[attnum] = 'n';
-                       inputTuple = heap_formtuple(tupType, tupValue, null_array);
-                       pfree(null_array);
-               }
 
                /*
-                * Store the representative input tuple (or faked-up null tuple)
+                * Store the representative input tuple (or NULL, if none)
                 * in the tuple table slot reserved for it.
                 */
                ExecStoreTuple(inputTuple,