Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 080212E3950 for ; Mon, 21 Jan 2008 18:03:33 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 35410-01-9 for ; Mon, 21 Jan 2008 18:03:27 -0400 (AST) Received: from news.hub.org (news.hub.org [200.46.204.72]) by postgresql.org (Postfix) with ESMTP id E785C2E38B8 for ; Mon, 21 Jan 2008 18:03:29 -0400 (AST) Received: from news.hub.org (news.hub.org [200.46.204.72]) by news.hub.org (8.14.1/8.14.1) with ESMTP id m0LM3OD7018180 for ; Mon, 21 Jan 2008 18:03:24 -0400 (AST) (envelope-from news@news.hub.org) Received: (from news@localhost) by news.hub.org (8.14.1/8.14.1/Submit) id m0LLttVp015687 for pgsql-performance@postgresql.org; Mon, 21 Jan 2008 17:55:55 -0400 (AST) (envelope-from news) From: Hannes Dorbath X-Newsgroups: pgsql.performance Subject: 8.3 synchronous_commit Date: Mon, 21 Jan 2008 22:55:16 +0100 Organization: Hub.Org Networking Services Lines: 22 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@news.hub.org User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) To: pgsql-performance@postgresql.org X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/163 X-Sequence-Number: 28402 I might completely misunderstand this feature. Shouldn't "synchronous_commit = off" improve performance? Whatever I do, I find "synchronous_commit = off" to degrade performance. Especially it doesn't like the CFQ I/O scheduler, it's not so bad with deadline. Synthetic load like pgbench -i -s 10 -U pgsql -d bench && pgbench -t 1000 -c 100 -U pgsql -d bench or the same with scale 100. Maybe it's just my test box.. single SATA-II drive, XFS on top of LVM. I'll retry without LVM once I have another drive.. I've seen LVM mess with other things in the past. -- Best regards, Hannes Dorbath