Received: from localhost (maia-5.hub.org [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id 1D9F99FB1CC for ; Mon, 27 Nov 2006 05:23:09 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-new, port 10024) with ESMTP id 24334-10 for ; Mon, 27 Nov 2006 05:23:01 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from noel.decibel.org (noel.decibel.org [67.100.216.10]) by postgresql.org (Postfix) with ESMTP id 7954B9FA23F for ; Mon, 27 Nov 2006 05:23:03 -0400 (AST) Received: by noel.decibel.org (Postfix, from userid 1001) id 8706B5643F; Mon, 27 Nov 2006 03:23:01 -0600 (CST) Received: (hashcash-sendmail, from uid 1001); Mon, 27 Nov 2006 03:22:56 -0600 Date: Mon, 27 Nov 2006 03:22:56 -0600 From: "Jim C. Nasby" To: Brian Wipf Cc: Tom Lane , Dave Cramer , pgsql-performance@postgresql.org, Guido Neitzer Subject: Re: shared_buffers > 284263 on OS X Message-ID: <20061127092256.GE67378@nasby.net> References: <82E59D2F-0946-4405-8F11-4CF5184A9399@fastcrypt.com> <412.1163874633@sss.pgh.pa.us> <817D9C4C-05F0-45FB-9D63-B63CFE2C009E@clickspace.com> <20061126232523.GD39519@nasby.net> <6ADBFE12-7A0D-4809-87CD-1F68755A8AD5@clickspace.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6ADBFE12-7A0D-4809-87CD-1F68755A8AD5@clickspace.com> X-Operating-System: FreeBSD 6.1-RELEASE-p10 amd64 X-Distributed: Join the Effort! http://www.distributed.net User-Agent: Mutt/1.5.13 (2006-08-11) X-Hashcash: 1:20:061127:brian@clickspace.com::DP+l5bl6JSQGNPnX:00000000000000000 0000000000000000000000005pIw X-Hashcash: 1:20:061127:tgl@sss.pgh.pa.us::cLeoh4MOn6y/Ocap:00000000000000000000 0000000000000000000000000LRV X-Hashcash: 1:20:061127:pg@fastcrypt.com::lKWk7JcKF2B53LoI:01LVy X-Hashcash: 1:20:061127:pgsql-performance@postgresql.org::fHvdV0VnQCqyJsXY:00000 00000000000000000000000010HG X-Hashcash: 1:20:061127:lists@event-s.net::xnQ4ekqic4flN5hy:00000000000000000000 0000000000000000000000000jzz X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200611/241 X-Sequence-Number: 22011 On Mon, Nov 27, 2006 at 07:23:47AM +0000, Brian Wipf wrote: > On 26-Nov-06, at 11:25 PM, Jim C. Nasby wrote: > >On Sat, Nov 18, 2006 at 08:13:26PM -0700, Brian Wipf wrote: > >>It certainly is unfortunate if Guido's right and this is an upper > >>limit for OS X. The performance benefit of having high shared_buffers > >>on our mostly read database is remarkable. > > > >Got any data about that you can share? People have been wondering > >about > >cases where drastically increasing shared_buffers makes a difference. > > Unfortunately, there are more differences than just the > shared_buffers setting in production right now; it's a completely > different set up, so the numbers I have to compare against aren't > particularly useful. > > When I get the chance, I will try to post data that shows the benefit > of having a higher value of shared_buffers for our usage pattern > (with all other settings being constant -- well, except maybe > effective_cache_size). Basically, in our current configuration, we > can cache all of the data we care about 99% of the time in about 3GB > of shared_buffers. Having shared_buffers set to 512MB as it was > originally, we were needlessly going to disk all of the time. Disk or to the kernel cache? -- Jim Nasby jim@nasby.net EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)