Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id C3BAA1337B9C for ; Wed, 22 Dec 2010 17:38:33 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 89943-05 for ; Wed, 22 Dec 2010 21:38:26 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id 427A01337B96 for ; Wed, 22 Dec 2010 17:38:25 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id oBMLcCmC010706; Wed, 22 Dec 2010 16:38:12 -0500 (EST) To: Scott Whitney cc: Kevin Grittner , pgsql-admin@postgresql.org Subject: Re: pg_clog not getting cleared In-reply-to: <21700506.3248.1293052359046.JavaMail.root@zimbra.int.journyx.com> References: <21700506.3248.1293052359046.JavaMail.root@zimbra.int.journyx.com> Comments: In-reply-to Scott Whitney message dated "Wed, 22 Dec 2010 15:12:39 -0600" Date: Wed, 22 Dec 2010 16:38:12 -0500 Message-ID: <10705.1293053892@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201012/167 X-Sequence-Number: 36396 Scott Whitney writes: > I understand the purpose of the clogs, but I would think that the transactions would have been frozen on all dbs (I've got about 300 in my cluster) by now. My logs go back to July 13th which, I think, is when the server was last restarted. It doesn't really try to remove clog entries that are younger than vacuum_freeze_table_age (see also vacuum_freeze_min_age). At two bits per transaction, the general feeling is that eating the disk space is better than forcing full-database vacuums more often. But if you're hot to have the space released sooner, those are the knobs to frob. regards, tom lane