trigger is holding up the data

I have a database with multiple tables. I have a trigger set on the event
table. When events occur a tuple is inserted into event and the trigger is
activated. In the trigger program I also want to look up data in other
tables based on the data inserted into the event table. Usually the data I
want to see from the other tables does not exist until the trigger program
has exited. How can I make the trigger activate only after all tables in
the database have been changed. It would still trigger on new events, but
it wouldn't run the program till all the tables that needed to be updated
were updated.

Thanks
Nate