Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id E6E9A6325C7 for ; Thu, 22 Jan 2009 17:52:21 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 79497-10 for ; Thu, 22 Jan 2009 17:52:17 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from smtp242.iad.emailsrvr.com (smtp242.iad.emailsrvr.com [207.97.245.242]) by mail.postgresql.org (Postfix) with ESMTP id A0091632582 for ; Thu, 22 Jan 2009 17:52:15 -0400 (AST) Received: from relay14.relay.iad.mlsrvr.com (localhost [127.0.0.1]) by relay14.relay.iad.mlsrvr.com (SMTP Server) with ESMTP id 2CF9D236C27; Thu, 22 Jan 2009 16:52:14 -0500 (EST) Received: by relay14.relay.iad.mlsrvr.com (Authenticated sender: chander-AT-otg-nc.com) with ESMTPSA id 05B93236B37; Thu, 22 Jan 2009 16:52:13 -0500 (EST) Message-ID: <4978EA8D.5010609@otg-nc.com> Date: Thu, 22 Jan 2009 16:52:13 -0500 From: Chander Ganesan User-Agent: Thunderbird 2.0.0.19 (Windows/20081209) MIME-Version: 1.0 To: Jan-Peter.Seifert@gmx.de CC: pgsql-admin@postgresql.org Subject: Re: PostgreSQL's query caching behaviour References: <20090122125328.233660@gmx.net> In-Reply-To: <20090122125328.233660@gmx.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200901/130 X-Sequence-Number: 31177 Jan-Peter.Seifert@gmx.de wrote: > Hello, > > I've a question regarding caching of results in the PostgreSQL-Server. > If you restart the server it will clear out the shared buffer pool, and subsequent queries would show the appropriate delay.. You can clear out the OS disk cache (on linux) using the commands: sync echo 1 > /proc/sys/vm/drop_caches That's likely what you are missing. -- Chander Ganesan Open Technology Group, Inc. One Copley Parkway, Suite 210 Morrisville, NC 27560 919-463-0999/877-258-8987 http://www.otg-nc.com Expert PostgreSQL, PostGIS, MapServer, Python, PHP, Django and other Open Source Training.