Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 36028133616B for ; Tue, 25 Jan 2011 18:27:21 -0400 (AST) 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 87393-08 for ; Tue, 25 Jan 2011 22:27:13 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mx3.uci.cu (ns3.uci.cu [200.55.140.180]) by mail.postgresql.org (Postfix) with SMTP id 3C4B61337B96 for ; Tue, 25 Jan 2011 18:27:10 -0400 (AST) Received: (qmail 19509 invoked by uid 507); 25 Jan 2011 22:27:02 -0000 Received: from 10.0.0.185 by ns3.uci.cu (envelope-from , uid 501) with qmail-scanner-2.01st (avp: 5.0.2.0. spamassassin: 3.0.6. perlscan: 2.01st. Clear:RC:1(10.0.0.185):. Processed in 0.797764 secs); 25 Jan 2011 22:27:02 -0000 Received: from unknown (HELO ucimail4.uci.cu) (10.0.0.185) by 0 with SMTP; 25 Jan 2011 22:27:01 -0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by ucimail4.uci.cu (Postfix) with ESMTP id 4D90D132482A; Tue, 25 Jan 2011 17:27:01 -0500 (CST) X-Virus-Scanned: amavisd-new at uci.cu Received: from ucimail4.uci.cu ([127.0.0.1]) by localhost (ucimail4.uci.cu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id e35qZYgxh-Qx; Tue, 25 Jan 2011 17:27:01 -0500 (CST) Received: from ucimail4.uci.cu (ucimail4.uci.cu [10.0.0.185]) by ucimail4.uci.cu (Postfix) with ESMTP id 1036F132480A; Tue, 25 Jan 2011 17:27:01 -0500 (CST) Date: Tue, 25 Jan 2011 17:27:01 -0500 (CST) From: "Ing. Marcos Ortiz Valmaseda" To: Anne Rosset Cc: pgsql-performance@postgresql.org Message-ID: <51831170.52414881295994420979.JavaMail.root@ucimail4.uci.cu> In-Reply-To: <1482241980.52411061295994101582.JavaMail.root@ucimail4.uci.cu> Subject: Re: Queries becoming slow under heavy load MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.0.0.186] X-Mailer: Zimbra 5.0.16_GA_2921.RHEL5_64 (ZimbraWebClient - FF3.0 (Linux)/5.0.16_GA_2921.RHEL5_64) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-0.011 tagged_above=-10 required=5 tests=BAYES_20=-0.001, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201101/238 X-Sequence-Number: 42025 When you say that with a lot of concurrent access, queries get very slow, H= ow many concurrent connections to your server have you had? more that max_connections=C2=B4value? If you want to have many concurrent connections, you should have consider t= o use a pooling connection system like pgbouncer or pgpool. Which are the values for: - work_mem - shared_buffers - maintenance_work_mem - effective_cache_size - effective_io_concurrency - server_version Which are your platform? Regards -- Ing. Marcos Lu=C3=ADs Ort=C3=ADz Valmaseda System Engineer -- Database Administrator Centro de Tecnolog=C3=ADas de Gesti=C3=B3n de Datos (DATEC) Universidad de las Ciencias Inform=C3=A1ticas http://postgresql.uci.cu