Bright D.L. wrote: > I would like to know why P1 can retrieve the data from the table while > P2 can't. At a guess: transactional visibility. P1 will have not yet committed its transaction, so the data isn't visible to P2 yet. Remember, PostgreSQL defaults to the READ COMMITTED isolation level and does not offer READ UNCOMMITTED for those rare situations where you might want it. By "send a trigger" I'm assuming you mean that you're using RAISE NOTICE and LISTEN. If P1 commits, then raises a notice to tell P2 about the changes, P2 should be able to see the changes immediately. Even if P2's transaction began before it receives the notice it should still see the changes (because of READ COMMITTED isolation). However, if a function or statement is running in P2 when P1 commits, the changes made by P1 will only become visible after that function or statement finishes. If I'm mistaken in my interpretation and P1 does in fact commit before notifying P2 of the changes, then there must be something else going on. Perhaps a bit more detail might help. -- Craig Ringer
