Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 884349FB55F for ; Mon, 28 May 2007 16:46:08 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 51577-04 for ; Mon, 28 May 2007 16:46:02 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from tamriel.snowman.net (tamriel.snowman.net [72.66.115.51]) by postgresql.org (Postfix) with ESMTP id B0CD69FB4E8 for ; Mon, 28 May 2007 16:46:04 -0300 (ADT) Received: by tamriel.snowman.net (Postfix, from userid 1000) id A0EE48415B; Mon, 28 May 2007 15:46:03 -0400 (EDT) Date: Mon, 28 May 2007 15:46:03 -0400 From: Stephen Frost To: Dave Cramer Cc: Heikki Linnakangas , postgresql performance list Subject: Re: PITR performance costs Message-ID: <20070528194603.GO7531@tamriel.snowman.net> Mail-Followup-To: Dave Cramer , Heikki Linnakangas , postgresql performance list References: <81165B3E-1099-4388-88F1-FA27A3AD92BC@fastcrypt.com> <465B03E5.1000109@enterprisedb.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="i7KxW38SoMauyveo" Content-Disposition: inline In-Reply-To: X-Editor: Vim http://www.vim.org/ X-Info: http://www.snowman.net X-Operating-System: Linux/2.6.18-4-vserver-amd64 (x86_64) X-Uptime: 15:43:40 up 21 days, 15:56, 15 users, load average: 0.11, 0.18, 0.14 User-Agent: Mutt/1.5.13 (2006-08-11) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200705/575 X-Sequence-Number: 24965 --i7KxW38SoMauyveo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Dave, et al, * Dave Cramer (pg@fastcrypt.com) wrote: > Don't the archived logs have to be copied as well as the regular WAL =20 > logs get recycled ? Yes, but I'd expect at the point they're being copied off to some other store (probably a seperate disk, or even over the network to another system, etc), they're probably in the system cache, so you're probably not going out to disk to get those blocks anyway. That might not be the case on a slow-write system, but in those cases it seems at least somewhat unlikely you'll be hit very hard by the occational 16MB copy off the disk... Thanks, Stephen > On 28-May-07, at 12:31 PM, Heikki Linnakangas wrote: >=20 > >Dave Cramer wrote: > >>Since PITR has to enable archiving does this not increase the =20 > >>amount of disk I/O required ? > > > >There's no difference in normal DML operations, but some bulk =20 > >operations like CREATE INDEX that don't otherwise generate WAL, =20 > >need to be WAL logged when archiving is enabled. > > > >--=20 > > Heikki Linnakangas > > EnterpriseDB http://www.enterprisedb.com >=20 >=20 > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? >=20 > http://www.postgresql.org/docs/faq --i7KxW38SoMauyveo Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGWzF7rzgMPqB3kigRAnBJAKCOXF9MsSpU64DCpoJzREQE+SaEuQCeIqaN dl3JKBpjRY/s2g31/vaj1cw= =F8bG -----END PGP SIGNATURE----- --i7KxW38SoMauyveo--