Make RelationForgetRelation error out if the relcache entry has nonzero

reference count.  This avoids leaving dangling pointers around, as in
recent bug report against sequences (bug# 671).

src/backend/utils/cache/relcache.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.163 2002/04/27 21:24:34 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.164 2002/05/22 15:57:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1841,8 +1841,13 @@ RelationForgetRelation(Oid rid)
 
 	RelationIdCacheLookup(rid, relation);
 
-	if (PointerIsValid(relation))
-	{
+	if (!PointerIsValid(relation))
+		return;					/* not in cache, nothing to do */
+
+	if (!RelationHasReferenceCountZero(relation))
+		elog(ERROR, "RelationForgetRelation: relation %u is still open", rid);
+
+	/* If local, remove from list */
 	if (relation->rd_myxactonly)
 	{
 		List	   *curr;
@@ -1858,7 +1863,7 @@ RelationForgetRelation(Oid rid)
 			prev = curr;
 		}
 		if (curr == NIL)
-				elog(FATAL, "Local relation %s not found in list",
+			elog(ERROR, "Local relation %s not found in list",
 				 RelationGetRelationName(relation));
 		if (prev == NIL)
 			newlyCreatedRelns = lnext(newlyCreatedRelns);
@@ -1869,7 +1874,6 @@ RelationForgetRelation(Oid rid)
 
 	/* Unconditionally destroy the relcache entry */
 	RelationClearRelation(relation, false);
-	}
 }
 
 /*