--- postgresql-8.3.7/src/bin/pg_dump/pg_dump.c.orig	2009-03-31 15:47:28.000000000 -0400
+++ postgresql-8.3.7/src/bin/pg_dump/pg_dump.c	2009-04-01 14:07:55.000000000 -0400
@@ -1759,7 +1759,18 @@
 
 	/* Cursor to get all BLOB comments */
 	if (AH->remoteVersion >= 70200)
-		blobQry = "DECLARE blobcmt CURSOR FOR SELECT loid, obj_description(loid, 'pg_largeobject') FROM (SELECT DISTINCT loid FROM pg_largeobject) ss";
+		/* Get comments for BLOBs that have a matching pg_description row. When there are many
+		 * (millions) of BLOBs without comments this avoids fetching and then ignoring them,
+		 * potentionally saving hours of backup time. */
+		blobQry = "DECLARE blobcmt CURSOR FOR SELECT loid, obj_description(loid, 'pg_largeobject') FROM ("
+				"SELECT DISTINCT loid FROM pg_description JOIN pg_largeobject "
+				"ON (pg_description.objoid = pg_largeobject.loid) "
+				"WHERE classoid = ("
+					"SELECT oid FROM pg_class WHERE relname = 'pg_largeobject' AND relnamespace = ("
+						"SELECT oid FROM pg_namespace WHERE nspname='pg_catalog'"
+					")"
+				") AND objsubid = 0"
+			  ") ss";
 	else if (AH->remoteVersion >= 70100)
 		blobQry = "DECLARE blobcmt CURSOR FOR SELECT loid, obj_description(loid) FROM (SELECT DISTINCT loid FROM pg_largeobject) ss";
 	else