Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id A00FE9FA31B for ; Tue, 2 Jan 2007 11:07:32 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-new, port 10024) with ESMTP id 16133-05 for ; Tue, 2 Jan 2007 11:07:20 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 9379D9FA2EE for ; Tue, 2 Jan 2007 11:07:26 -0400 (AST) 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 l02F7Pxu003426; Tue, 2 Jan 2007 10:07:25 -0500 (EST) To: =?iso-8859-1?q?Rolf=20=D8stvik?= cc: pgsql-performance@postgresql.org Subject: Re: Worse perfomance on 8.2.0 than on 7.4.14 In-reply-to: <20070102124518.1503.qmail@web26301.mail.ukl.yahoo.com> References: <20070102124518.1503.qmail@web26301.mail.ukl.yahoo.com> Comments: In-reply-to =?iso-8859-1?q?Rolf=20=D8stvik?= message dated "Tue, 02 Jan 2007 13:45:18 +0100" Date: Tue, 02 Jan 2007 10:07:24 -0500 Message-ID: <3425.1167750444@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200701/15 X-Sequence-Number: 22616 =?iso-8859-1?q?Rolf=20=D8stvik?= writes: > If you (Tom) still want me to do the following steps > then please tell me. Please --- I'm still curious why the estimated cost changed so much from 7.4 to 8.2. I can believe a marginal change in cost leading to a plan switch, but comparing the total-cost numbers shows that 8.2 must think that indexscan is a whole lot more expensive than 7.4 did, which seems odd. For the most part 8.2 ought to think nestloop-with-inner-indexscan is cheaper than 7.4 did, because we now account for caching effects across repeated iterations of the inner scan. regards, tom lane