Trigger for Large Object Modification - Mailing list pgsql-sql

Hello,

I created a table with a OID Column to carry the identifier for a Large 
Object. 
Now i want to run a trigger is the data of the large object has changed. To do 
this I created an ON UPDATE-trigger on the table, but the trigger does get 
fired if i only change the data of the large object (not its id).

Is there any way to get notified if a large object has changed?

Thanks in advance,
A. Roth