From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 3 Nov 2005 17:34:03 +0000 (+0000)
Subject: Fix the recently-added code that eliminates unnecessary SubqueryScan nodes
X-Git-Url: http://waps.l3s.uni-hannover.de/gitweb/?a=commitdiff_plain;h=b17ae35d0df107488af15db05e1d01dad2040d1c;p=users%2Fbernd%2Fpostgres.git

Fix the recently-added code that eliminates unnecessary SubqueryScan nodes
from a finished plan tree.  We have to copy the output column names
(resname fields) from the SubqueryScan down to its child plan node;
else, if this is the topmost level of the plan, the wrong column names
will be delivered to the client.  Per bug #2017 reported by Jolly Chen.
---

diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index bd09e9b698..5b2156ee29 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -359,6 +359,8 @@ set_subqueryscan_references(SubqueryScan *plan, List *rtable)
 		 */
 		int			rtoffset = list_length(rtable);
 		List	   *sub_rtable;
+		ListCell   *lp,
+				   *lc;
 
 		sub_rtable = copyObject(rte->subquery->rtable);
 		range_table_walker(sub_rtable,
@@ -378,6 +380,19 @@ set_subqueryscan_references(SubqueryScan *plan, List *rtable)
 
 		result->initPlan = list_concat(plan->scan.plan.initPlan,
 									   result->initPlan);
+
+		/*
+		 * we also have to transfer the SubqueryScan's result-column names
+		 * into the subplan, else columns sent to client will be improperly
+		 * labeled if this is the topmost plan level.
+		 */
+		forboth(lp, plan->scan.plan.targetlist, lc, result->targetlist)
+		{
+			TargetEntry *ptle = (TargetEntry *) lfirst(lp);
+			TargetEntry *ctle = (TargetEntry *) lfirst(lc);
+
+			ctle->resname = ptle->resname;
+		}
 	}
 	else
 	{