Received: from localhost (wm.hub.org [200.46.204.128]) by postgresql.org (Postfix) with ESMTP id 5B4739FB322 for ; Fri, 3 Nov 2006 11:27:43 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.128]) (amavisd-new, port 10024) with ESMTP id 59366-10 for ; Fri, 3 Nov 2006 15:27:37 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey- Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 91F739FA158 for ; Fri, 3 Nov 2006 11:27:37 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id kA3FPlfp002401; Fri, 3 Nov 2006 10:25:47 -0500 (EST) To: creimer@brturbo.com.br cc: Richard Huxton , pgsql-performance@postgresql.org Subject: Re: Context switch storm In-reply-to: References: <454B3B75.6@archonet.com> Comments: In-reply-to creimer@brturbo.com.br message dated "Fri, 03 Nov 2006 11:28:36 -0200" Date: Fri, 03 Nov 2006 10:25:47 -0500 Message-ID: <2400.1162567547@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200611/51 X-Sequence-Number: 21821 creimer@brturbo.com.br writes: > And why this happens only with 8.0 and 8.1 and not with the 7.4? 8.0 and 8.1 are vulnerable to this behavior because of conflicts for access to pg_subtrans (which didn't exist in 7.4). The problem occurs when you have old open transactions, causing the window over which pg_subtrans must be accessed to become much wider than normal. 8.2 should eliminate or at least alleviate the issue, but in the meantime see if you can get your applications to not sit on open transactions. regards, tom lane