Fix a couple of planner bugs introduced by the new ability to discard

ORDER BY <constant> as redundant.  One is that this means query_planner()
has to canonicalize pathkeys even when the query jointree is empty;
the canonicalization was always a no-op in such cases before, but no more.
Also, we have to guard against thinking that a set-returning function is
"constant" for this purpose.  Add a couple of regression tests for these
evidently under-tested cases.  Per report from Greg Stark and subsequent
experimentation.

1 files changed, 13 insertions, 1 deletions

diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c
index c31f7d5aa65..f8ff3a71508 100644
--- a/src/backend/optimizer/plan/planmain.c
+++ b/src/backend/optimizer/plan/planmain.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.101 2007/05/04 01:13:44 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.102 2007/07/07 20:46:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -106,9 +106,21 @@ query_planner(PlannerInfo *root, List *tlist,
 	 */
 	if (parse->jointree->fromlist == NIL)
 	{
+		/* We need a trivial path result */
 		*cheapest_path = (Path *)
 			create_result_path((List *) parse->jointree->quals);
 		*sorted_path = NULL;
+		/*
+		 * We still are required to canonicalize any pathkeys, in case
+		 * it's something like "SELECT 2+2 ORDER BY 1".
+		 */
+		root->canon_pathkeys = NIL;
+		root->query_pathkeys = canonicalize_pathkeys(root,
+													 root->query_pathkeys);
+		root->group_pathkeys = canonicalize_pathkeys(root,
+													 root->group_pathkeys);
+		root->sort_pathkeys = canonicalize_pathkeys(root,
+													root->sort_pathkeys);
 		return;
 	}