Received: from localhost (wm.hub.org [200.46.204.128]) by postgresql.org (Postfix) with ESMTP id 179DD9FB556 for ; Sat, 21 Oct 2006 00:43:26 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.128]) (amavisd-new, port 10024) with ESMTP id 99853-02-5 for ; Sat, 21 Oct 2006 03:42:28 +0000 (UTC) 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 E1C839FB5D6 for ; Sat, 21 Oct 2006 00:30:34 -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 k9L3UWct020907; Fri, 20 Oct 2006 23:30:32 -0400 (EDT) To: Stuart Bishop cc: pgsql-performance@postgresql.org Subject: Re: Slow functional indexes? In-reply-to: <45387666.204@canonical.com> References: <45387666.204@canonical.com> Comments: In-reply-to Stuart Bishop message dated "Fri, 20 Oct 2006 14:10:30 +0700" Date: Fri, 20 Oct 2006 23:30:32 -0400 Message-ID: <20906.1161401432@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200610/452 X-Sequence-Number: 21581 Stuart Bishop writes: > I would like to understand what causes some of my indexes to be slower to > use than others with PostgreSQL 8.1. I was about to opine that it was all about different levels of correlation between the index order and physical table order ... but your experiments with freshly clustered indexes seem to cast doubt on that idea. Are you sure your function is really immutable? A buggy function could possibly lead to a "clustered" index not being in physical order. regards, tom lane