Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id C2F9BB5DC18 for ; Mon, 13 Jun 2011 15:25:35 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 28292-05 for ; Mon, 13 Jun 2011 18:25:29 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mail-out1.uio.no (mail-out1.uio.no [129.240.10.57]) by mail.postgresql.org (Postfix) with ESMTP id B97FCB5DBD5 for ; Mon, 13 Jun 2011 15:25:28 -0300 (ADT) Received: from mail-mx3.uio.no ([129.240.10.44]) by mail-out1.uio.no with esmtp (Exim 4.75) (envelope-from ) id 1QWBpH-0007YL-SH; Mon, 13 Jun 2011 20:25:27 +0200 Received: from ti0153a380-0052.bb.online.no ([88.89.54.52] helo=[10.1.1.200]) by mail-mx3.uio.no with esmtpsa (SSLv3:CAMELLIA256-SHA:256) user rafael (Exim 4.76) (envelope-from ) id 1QWBpH-0006lS-BC; Mon, 13 Jun 2011 20:25:27 +0200 Subject: Re: Information about WAL Configuration needs an update From: Rafael Martinez To: Robert Haas Cc: pgsql-docs@postgresql.org In-Reply-To: References: <4DE89072.7070305@usit.uio.no> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-+dZ1iFtawMBkPxeeT39n" Organization: University of Oslo Date: Mon, 13 Jun 2011 20:25:11 +0200 Message-ID: <1307989511.2862.810.camel@core2> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 X-UiO-Ratelimit-Test: rcpts/h 2 msgs/h 1 sum rcpts/h 4 sum msgs/h 1 total rcpts 2509 max rcpts/h 15 ratelimit 0 X-UiO-Spam-info: not spam, SpamAssassin (score=-5.0, required=5.0, autolearn=disabled, UIO_MAIL_IS_INTERNAL=-5, uiobl=NO, uiouri=NO) X-UiO-Scanned: 1117A82A780F311DD637581F9D3D48981402EDF4 X-UiO-SPAM-Test: remote_host: 88.89.54.52 spam_score: -49 maxlevel 80 minaction 2 bait 0 mail/h: 1 total 20 max/h 5 blacklist 0 greylist 0 ratelimit 0 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-5 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201106/51 X-Sequence-Number: 6825 --=-+dZ1iFtawMBkPxeeT39n Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2011-06-13 at 13:24 -0400, Robert Haas wrote: > On Fri, Jun 3, 2011 at 3:42 AM, Rafael Martinez > > > > You can see the graph with the generation of WAL files + some extra > > information for this test here: http://folk.uio.no/rafael/total_wal/ > > > > What do you think? Shouldn't we update the documentation with some > > information about this? >=20 > Perhaps, but we'd have to think of something intelligent to say about > it first. We can't remove the old WAL files until we successfully > checkpoint, and so I think if checkpoints are taking a very long to > complete or failing altogether, there's actually no upper bound. I > don't think we have any kind of "hard stop" where, if no log space is > available, we just refuse to process write transactions - such a thing > would seem to be rather dangerous. >=20 Well, a good start will be to try to identify or describe the situations where checkpoints can take very long to complete or fail altogether. I have the first one: Creating a large GIN index on a tsvector column. I don't know why, maybe somebody who knows postgres internals can explain why a creation of an index can create this situation. regards, --=20 Rafael Martinez Guerrero Center for Information Technology University of Oslo, Norway PGP Public Key: http://folk.uio.no/rafael/ --=-+dZ1iFtawMBkPxeeT39n Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEABECAAYFAk32VgUACgkQBhuKQurGihTabQCgoLzNcZdFlK79/0uOsoQCwKEm MFsAniMhd7hQZeX6xOwN/YhlWi+b9F9M =/am/ -----END PGP SIGNATURE----- --=-+dZ1iFtawMBkPxeeT39n--