Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 16CDB2E0346 for ; Mon, 21 Jan 2008 18:11:15 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 07008-01 for ; Mon, 21 Jan 2008 18:11:10 -0400 (AST) Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.189]) by postgresql.org (Postfix) with ESMTP id 01DFF2E02B4 for ; Mon, 21 Jan 2008 18:11:09 -0400 (AST) Received: by nf-out-0910.google.com with SMTP id f5so311821nfh.23 for ; Mon, 21 Jan 2008 14:11:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=rWgkANSm0WZBaPiOQRNnZe0lRyVKUzCgRf2F43D4ufk=; b=gK3Sg9cnTfG8NtvtTjmm7z17fzcNjME4myUPI4HeIUfgCHRggl+Oyp8rgj0qxv6HXnxfMtN+YB36Fme1T4/5l1heF9z0vz8uiL416cbOhhjsuceXlr1Gb9O4litMybYQxeKkotgz3Ore7QqArLW368qO69cwScAzljhPiLzW7uM= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=mIxqXfEPNGH2/yQ+lr1R74ZLfq3GoLLlCUhUSIzDWIx0XCqQsK2Y1Q5rV4IMdQx5wzOwT/jlepe1SFGY9rptiEw12heKlbkoujWo2BZzwkGEeTU9Wr+rA4UrpwFUM5w2Wf1SzLOZkHxKU4iwcCHCryk/qzE+5OnXZIAb+JN4Ca0= Received: by 10.78.185.15 with SMTP id i15mr10067988huf.15.1200953467765; Mon, 21 Jan 2008 14:11:07 -0800 (PST) Received: by 10.78.35.7 with HTTP; Mon, 21 Jan 2008 14:11:07 -0800 (PST) Message-ID: <162867790801211411j48e2d435lc7bba2b735ccfe45@mail.gmail.com> Date: Mon, 21 Jan 2008 23:11:07 +0100 From: "Pavel Stehule" To: "Hannes Dorbath" Subject: Re: 8.3 synchronous_commit Cc: pgsql-performance@postgresql.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/164 X-Sequence-Number: 28403 Hello synchronous_commit = off is well for specific load, try only one connect pgbench ~ it is analogy for database import or some administrator's work. Regards Pavel Stehule On 21/01/2008, Hannes Dorbath wrote: > 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 > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq >