Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id A7CD51337BCD for ; Mon, 28 Mar 2011 03:18:53 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 99423-02-4 for ; Mon, 28 Mar 2011 06:18:45 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.17.9]) by mail.postgresql.org (Postfix) with ESMTP id DC0F41337CEE for ; Mon, 28 Mar 2011 03:03:08 -0300 (ADT) Received: from [192.168.1.6] (mail.highperformancepostgresql.com [71.179.240.8]) by mrelayeu.kundenserver.de (node=mrbap3) with ESMTP (Nemesis) id 0MEWGP-1QAxIg2uML-00Fmgz; Mon, 28 Mar 2011 08:03:08 +0200 Message-ID: <4D902482.9010705@2ndQuadrant.com> Date: Mon, 28 Mar 2011 02:02:42 -0400 From: Greg Smith User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20110307 Icedove/3.0.11 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: buffercache/bgwriter References: <6010559739.20110323141959@erwied.eu> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:1q3i+xBZKMho8FnHVkp35urMG7K3Sw8w/i8c09CEy7X bxZ2sZFW/jXh1uKQiaTakzP9ruu9nYGla/KX/zbYH+3oziWLOg E4+bsGu0mGtPVuh2RD7XApr1hud4UZUC/QzhM6pNlB1e2K/voT axPqmn5lkqfOKynms0QAth39noolkuCYo6J0G2pvdY3y9jzx+q DpeSIg730k5YAHogwisvItGOhE2/wK2wl43GK1PyXQ= X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.9 tagged_above=-10 required=5 tests=BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001 X-Spam-Level: X-Archive-Number: 201103/341 X-Sequence-Number: 43020 On 03/24/2011 05:19 AM, Uwe Bartels wrote: > It would also be good to see how many buffers were written by backend > processes grouped by Buffer Access Strategy - to better distinguish > evil backend writes from wanted backend writes. Since all these writes are being cached by the operating system, which strategy writes them out isn't that useful to track. The only really "evil" type of writes are ones where the background writer doesn't absorb the fsync calls and the backends have to do that themselves. And as of V9.1, that is something you can distinguish in pg_stat_bgwriter (and it's also less likely to happen, too) -- Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us "PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books