Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id 2105FB5DBD8 for ; Tue, 24 May 2011 20:26:34 -0300 (ADT) 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 04180-04 for ; Tue, 24 May 2011 23:26:26 +0000 (UTC) X-Greylist: delayed 00:07:04.53735 by SQLgrey-1.7.6 Received: from na3sys009aog109.obsmtp.com (na3sys009aog109.obsmtp.com [74.125.149.201]) by mail.postgresql.org (Postfix) with ESMTP id EBE6CB5D801 for ; Tue, 24 May 2011 20:26:25 -0300 (ADT) Received: from mail-bw0-f50.google.com ([209.85.214.50]) (using TLSv1) by na3sys009aob109.postini.com ([74.125.148.12]) with SMTP ID DSNKTdw+obOvRwNra6U1KQTctIfQDPnD2Omi@postini.com; Tue, 24 May 2011 16:26:26 PDT Received: by mail-bw0-f50.google.com with SMTP id 2so7771942bwz.37 for ; Tue, 24 May 2011 16:26:25 -0700 (PDT) MIME-Version: 1.0 Received: by 10.204.82.224 with SMTP id c32mr3735124bkl.161.1306279160066; Tue, 24 May 2011 16:19:20 -0700 (PDT) Received: by 10.204.33.86 with HTTP; Tue, 24 May 2011 16:19:20 -0700 (PDT) Date: Tue, 24 May 2011 16:19:20 -0700 Message-ID: Subject: Seems like a large amount of xlog files From: Michael Holt To: pgsql-admin@postgresql.org Content-Type: multipart/alternative; boundary=0016e6dd8eb850347804a40dd170 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-0.195 tagged_above=-10 required=5 tests=BAYES_00=-1.9, HTML_IMAGE_ONLY_20=1.546, HTML_MESSAGE=0.001, HTML_SHORT_LINK_IMG_3=0.148, T_REMOTE_IMAGE=0.01 X-Spam-Level: X-Archive-Number: 201105/162 X-Sequence-Number: 37599 --0016e6dd8eb850347804a40dd170 Content-Type: text/plain; charset=ISO-8859-1 We're trying to do some performance tuning on a couple of postgres boxes and I've noticed there seems to be a lot of activity in the pg_xlog folder. There seems to consitently be 132 files with many being written almost every minute. Looking just now I see 40 written in the last minute and 48 in the minute before that. I'm having some difficulty determining why there are so many WAL files being written so frequently as this is normally a low-write/high read server. There are some things causing implicit transactions in some old code, but they do not actually write to any tables. So i have two questions: 1) Does simply running a transaction (implicit or explicit) cause writing to the WAL? 2) Is there any simple way to track what may be causing WAL writes? Alternatively, is there a simple way to see what is being recorded in these files? -- *Michael Holt*, *Database Administrator* | A.E.R.S. & TERAPEAK 2307-4464 Markham Street, Victoria, BC, CANADA V8Z 7X8 +1 250 483 3271 (FAX) www.terapeak.com | www.aers.ca | [image: facebook]| [image: twitter] --0016e6dd8eb850347804a40dd170 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable We're trying to do some performance tuning on a couple of postgres boxe= s and I've noticed there seems to be a lot of activity in the pg_xlog f= older. There seems to consitently be 132 files with many being written almo= st every minute. Looking just now I see 40 written in the last minute and 4= 8 in the minute before that. I'm having some difficulty determining why= there are so many WAL files being written so frequently as this is normall= y a low-write/high read server. There are some things causing implicit tran= sactions in some old code, but they do not actually write to any tables. So= i have two questions: 1) Does simply running a transaction (implicit or ex= plicit) cause writing to the WAL? 2) Is there any simple way to track what = may be causing WAL writes?

Alternatively, is there a simple way to see what is being recorded = in these files?

--
<= b>Michael Holt, Database Administrator=A0=A0|=A0=A0A.E.R.S. & TERAPEAK
2307-4464 Markham S= treet, Victoria, BC, CANADA V8Z 7X8
+1 250 483 3271 (F= AX)
www.terapeak.com | www.aers.ca | 3D"facebook"

--0016e6dd8eb850347804a40dd170--