Re: create language ... if not exists - Mailing list pgsql-patches

I wrote:
> ... However, I seem to recall
> that in the discussions leading up to implementing DROP IF EXISTS,
> we considered and specifically rejected CREATE IF NOT EXISTS.  Don't
> have time right now to troll the archives for the reasoning.

[ back from dinner party... ]  Here's the thread I was remembering:
http://archives.postgresql.org/pgsql-hackers/2005-10/msg00632.php

The key argument seems to be that it's quite unclear what the state
following CREATE IF NOT EXISTS (CINE) should be, if the object does
exist but not with the same properties specified in the CINE command.
CREATE OR REPLACE resolves that by making it clear that it's gonna be
what the command says.  Perhaps there is a use-case for the alternate
behavior where the pre-existing object doesn't get modified, but I'm
not too sure what it would be.

            regards, tom lane