Repair remarkably-inefficient query for dumping large object comments: it

was invoking obj_description() for each large object chunk, instead of once
per large object.  This code is new as of 8.1, which may explain why the
problem hadn't been noticed already.

src/bin/pg_dump/pg_dump.c

@@ -12,7 +12,7 @@
  *	by PostgreSQL
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/bin/pg_dump/pg_dump.c,v 1.437 2006/06/07 22:24:45 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/bin/pg_dump/pg_dump.c,v 1.438 2006/06/09 19:46:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1575,9 +1575,9 @@ dumpBlobComments(Archive *AH, void *arg)
 
 	/* Cursor to get all BLOB comments */
 	if (AH->remoteVersion >= 70200)
-		blobQry = "DECLARE blobcmt CURSOR FOR SELECT DISTINCT loid, obj_description(loid, 'pg_largeobject') FROM pg_largeobject";
+		blobQry = "DECLARE blobcmt CURSOR FOR SELECT loid, obj_description(loid, 'pg_largeobject') FROM (SELECT DISTINCT loid FROM pg_largeobject) ss";
 	else if (AH->remoteVersion >= 70100)
-		blobQry = "DECLARE blobcmt CURSOR FOR SELECT DISTINCT loid, obj_description(loid) FROM pg_largeobject";
+		blobQry = "DECLARE blobcmt CURSOR FOR SELECT loid, obj_description(loid) FROM (SELECT DISTINCT loid FROM pg_largeobject) ss";
 	else
 		blobQry = "DECLARE blobcmt CURSOR FOR SELECT oid, (SELECT description FROM pg_description pd WHERE pd.objoid=pc.oid) FROM pg_class pc WHERE relkind = 'l'";