Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1US20P-0003Uo-1f for pgsql-performance@arkaria.postgresql.org; Tue, 16 Apr 2013 09:16:49 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.72) (envelope-from ) id 1US20O-00082H-FZ for pgsql-performance@arkaria.postgresql.org; Tue, 16 Apr 2013 09:16:48 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1US20N-00082C-Ky for pgsql-performance@postgresql.org; Tue, 16 Apr 2013 09:16:47 +0000 Received: from smtp01.smtpout.orange.fr ([80.12.242.123] helo=smtp.smtpout.orange.fr) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1US20J-0007g7-I6 for pgsql-performance@postgresql.org; Tue, 16 Apr 2013 09:16:47 +0000 Received: from axege.com ([82.127.232.162]) by mwinf5d36 with ME id QZGg1l00V3WtTCJ03ZGg01; Tue, 16 Apr 2013 11:16:41 +0200 Received: from localhost (localhost [127.0.0.1]) by axege.com (Postfix) with ESMTP id 68E5943DE02 for ; Tue, 16 Apr 2013 11:16:40 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at myhostname="axege.com." Received: from axege.com ([127.0.0.1]) by localhost (axege.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SXaU8Ezim9fw for ; Tue, 16 Apr 2013 11:16:39 +0200 (CEST) Received: from [10.0.0.84] (unknown [10.0.0.84]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by axege.com (Postfix) with ESMTPSA id B0B3543DE01 for ; Tue, 16 Apr 2013 11:16:39 +0200 (CEST) Message-ID: <516D16F7.10706@axege.com> Date: Tue, 16 Apr 2013 11:16:39 +0200 From: Franck Routier User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130404 Thunderbird/17.0.5 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: Postgresql performance degrading... how to diagnose the root cause References: <5155A33A.4090000@axege.com> In-Reply-To: <5155A33A.4090000@axege.com> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms030502060708050805000106" X-Pg-Spam-Score: -1.1 (-) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org Ceci est un message signé cryptographiquement au format MIME. --------------ms030502060708050805000106 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Le 29/03/2013 15:20, Franck Routier a =E9crit : > Hi, > > I have a postgresql database (8.4) running in production whose=20 > performance is degrading. > There is no single query that underperforms, all queries do. > Another interesting point is that a generic performance test=20 > (https://launchpad.net/tpc-b) gives mediocre peformance when run on=20 > the database, BUT the same test on a newly created database, on the=20 > same pg cluster, on the same tablespace, does perform good. > > So the problem seems to be limited to this database, even on newly=20 > created tables... > > What should I check to find the culprit of this degrading performance ?= > > Franck > Just for the record, the problem turned out to be a too high=20 default_statistics_target (4000) that was causing the planner to take up = to seconds just to evaluate the better plan (probably in eqjoinsel() ). See thread titled "What happens between end of explain analyze and end=20 of query execution ?" on this list for details. Thanks again to those who responded. 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