Martijn van Oosterhout <kleptog@xxxxxxxxx> writes: > On Wed, Oct 11, 2006 at 08:56:23PM +0200, Rafal Pietrak wrote: >> Are there any plans for anything like that (referencing keys in system >> tables from public schemas)? > Not really. The primary objection is that every lookup in the backend > on the system catalogs (of which there are many) would have to be > modified to check for triggers. This would be bad for performence > against a handful of cases where it would be useful. There are also some interesting issues of circularity --- eg, you will never be able to have triggers on pg_proc or pg_trigger, because that would create an infinite recursion in relcache load. Not to mention risks such as a broken trigger on pg_trigger keeping you from removing it... It's possible that we could support AFTER triggers on certain non-core catalogs. I can only recall people ever asking for this feature in connection with the user/group catalogs, so covering those might be enough in practice; that'd certainly be lots less invasive than trying to make it work everywhere. regards, tom lane
