create trigger hangs I have a trigger function that just copies inserted values to another table.
Then, each night I need to drop and recreate this trigger for some export operation. 

--trigger function 
CREATE OR REPLACE FUNCTION mev_copy() RETURNS trigger AS $mev_copy$
        BEGIN   INSERT INTO measurement_events_copy SELECT NEW.*;
            RETURN NEW;
        END;


The problem is that sometimes the trigger cannot start: CREATE TRRIGGER command never returns, and the DB seems locked-up and puts all queries in "PARSE waiting" status.  Yesterday it was like that for 6 hours until I killed the create trigger.

The problem manifests consistently when table measurement_events is being autovacuumed. At the same time there is a new pending AccessExclusiveLock request for this table.

This is the create trigger, nothing special:

--CREATE TRIGGER that hangs sometimes
CREATE TRIGGER mev_copy AFTER INSERT ON measurement_events FOR EACH ROW EXECUTE PROCEDURE mev_copy();


Postgres version is 8.4.
Any insights?
Cannot be done with PG 8.4.
It's actually on the TODO of postgres to reduce trigger requirements: 


https://wiki.postgresql.org/wiki/Todo
http://www.postgresql.org/message-id/1213387611.25121.250.camel@ebony.site