Automatically deleting dangling large object references.

I was thinking of trying something like the following to automatically delete
rows from tables that reference large objects when the large object is
unlinked.  It would depend on pg_class having a PRIMARY key (on the hidden
'oid' column in this possible example):

-- this is a generic table to just hold large objects
CREATE TABLE lobjs (
	id		SERIAL	CONSTRAINT lobjs_id_con
		PRIMARY KEY,
		-- other tables referencing this would also react.
 	lo_oid		OID	CONSTRAINT lobjs_lo_oid_con NOT NULL,
		-- holds an actual large object id.
 	lo_ref_oid	OID	CONSTRAINT lobjs_lo_ref_oid_con
			REFERENCES pg_class
			ON UPDATE CASCADE
			ON DELETE CASCADE
			INITIALLY DEFERRED
);

CREATE RULE set_lo_ref_oid AS
	ON INSERT TO lobjs
	DO
		UPDATE lobjs
		SET lo_ref_oid = pg_class.oid
		FROM pg_class
		WHERE pg_class.relname = "xinx" || new.lo_oid;

Something like that (I'd have to check this sql to make sure its right). I don't
think there is a primary key on the system tables.  I wonder if it would cause
problems if there where?

Anyway, does anyone know of a way to accomplish something like what I am trying
to do with the large objects?

-- 
Robert B. Easter
reaster@comptechnews.com