Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id 4FCF19F9ED0 for ; Thu, 12 Oct 2006 13:24:30 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 69797-07 for ; Thu, 12 Oct 2006 13:24:20 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id E6E1F9F9EC9 for ; Thu, 12 Oct 2006 13:24:19 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id k9CGOGFw011205; Thu, 12 Oct 2006 12:24:16 -0400 (EDT) To: Heikki Linnakangas cc: Bruce Momjian , "Jim C. Nasby" , pgsql-performance@postgresql.org Subject: Re: Hints proposal In-reply-to: <452E6565.4010400@enterprisedb.com> References: <200610121519.k9CFJA416544@momjian.us> <452E6565.4010400@enterprisedb.com> Comments: In-reply-to Heikki Linnakangas message dated "Thu, 12 Oct 2006 16:55:17 +0100" Date: Thu, 12 Oct 2006 12:24:16 -0400 Message-ID: <11204.1160670256@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.09 tagged_above=0 required=5 tests=AWL, SPF_HELO_PASS, SPF_PASS X-Spam-Level: X-Archive-Number: 200610/239 X-Sequence-Number: 21368 Heikki Linnakangas writes: > BTW: Do we make use of CHECK constraints in the planner? Only for "constraint exclusion", and at the moment that's off by default. The gating problem here is that if the planner relies on a CHECK constraint, and then you drop the constraint, the previously generated plan might start to silently deliver wrong answers. So I'd like to see a plan invalidation mechanism in place before we go very far down the path of relying on constraints for planning. That's something I'm going to try to make happen for 8.3, though. regards, tom lane