Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 087BD64FD18 for ; Tue, 28 Oct 2008 07:10:59 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 94996-03 for ; Tue, 28 Oct 2008 07:10:54 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail128074.authsmtp.net (outmail128074.authsmtp.net [62.13.128.74]) by postgresql.org (Postfix) with ESMTP id D627364FCEE for ; Tue, 28 Oct 2008 07:10:52 -0300 (ADT) Received: from mail-c193.authsmtp.com (mail-c193.authsmtp.com [62.13.128.118]) by punt4.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id m9SAAn87008923; Tue, 28 Oct 2008 10:10:49 GMT Received: from [192.168.0.3] (85-211-99-122.dyn.gotadsl.co.uk [85.211.99.122]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id m9SAAmV0035074; Tue, 28 Oct 2008 10:10:48 GMT Subject: Re: VACUUMs and WAL From: Simon Riggs To: Hannu Krosing Cc: pgsql-hackers In-Reply-To: <1225187130.7721.5.camel@huvostro> References: <1225183785.3971.114.camel@ebony.2ndQuadrant> <1225187130.7721.5.camel@huvostro> Content-Type: text/plain Date: Tue, 28 Oct 2008 10:10:45 +0000 Message-Id: <1225188645.3971.118.camel@ebony.2ndQuadrant> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit X-Server-Quench: b1cf6c24-a4d8-11dd-8a51-002264978518 X-AuthRoute: OCdxZQATClZOTQEd DAteCiNZVAwpPBRK HVkIKg5MJUcNSQVJ NksadBtFag1bYlpF HGQLW1xEUV17WGN/ bwMfZQBDYEtPQQxj TklLQE1QEQdtHhxP Wxd9I2gvEQVGe3tw YkIsX3FfVQoodBUr RB1WEXBXYTNodWEe BBRFf1JRcR5Kfh1H bFR2U3sIYG1JBC9q VzwTFhsSEA9kHWxr ayowEHcJCU8NEnYD bjRq X-Authentic-SMTP: 61633235383639.pelican.dmpriest.net.uk:1378/Kp X-Report-SPAM: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-Virus-Status: No virus detected - but ensure you scan with your own anti-virus system! X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200810/1378 X-Sequence-Number: 126395 On Tue, 2008-10-28 at 11:45 +0200, Hannu Krosing wrote: > On Tue, 2008-10-28 at 08:49 +0000, Simon Riggs wrote: > > Looking at a VACUUM's WAL records makes me think twice about the way we > > issue a VACUUM. > > > > 1. First we scan the heap, issuing a HEAP2 clean record for every block > > that needs cleaning. > > IIRC the first heap pass just collects info and does nothing else. > Is this just an empty/do-nothing WAL record ? 8.3 changed that; it used to work that way. I guess I never looked at the amount of WAL being generated. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support