From:
Simon Riggs <simon(at)2ndquadrant(dot)com>
To:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc:
Greg Stark <gsstark(at)mit(dot)edu>,Mark Cave-Ayland <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>,'Manfred Koizar' <mkoi-pg(at)aon(dot)at>,'Bruce Momjian' <pgman(at)candle(dot)pha(dot)pa(dot)us>,pgsql-hackers(at)postgresql(dot)org
Subject:
Re: Cost of XLogInsert CRC calculations
Date:
2005-06-01 08:50:09
Message-ID:
1117615809.3844.893.camel@localhost.localdomain (view raw or flat )
Thread:
2005-03-07 11:04:00 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-03-07 14:39:50 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-03-07 17:45:57 from Gaetano Mendola <mendola(at)bigfoot(dot)com>
2005-03-07 23:53:59 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-03-08 01:50:01 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-03-08 02:18:57 from Greg Stark <gsstark(at)mit(dot)edu>
2005-03-08 08:31:35 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-05-10 14:13:48 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-10 14:30:55 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-10 14:34:33 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-05-10 21:46:05 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-05-10 22:22:28 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-10 22:57:52 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-05-11 12:40:08 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-11 19:32:04 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-05-12 01:46:07 from Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
2005-05-12 12:48:48 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-12 15:52:16 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-05-16 08:03:51 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-16 11:12:55 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-16 13:07:51 from Hannu Krosing <hannu(at)skype(dot)net>
2005-05-16 14:01:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-16 14:32:15 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-16 16:35:35 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-17 14:02:14 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-17 17:15:25 from Kris Jurka <books(at)ejurka(dot)com>
2005-05-17 20:22:52 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2005-05-17 22:29:54 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-05-18 02:37:05 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-18 03:51:52 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-05-18 04:25:31 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-18 05:04:41 from Greg Stark <gsstark(at)mit(dot)edu>
2005-05-18 05:12:26 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-18 05:24:15 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-05-18 08:23:30 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-18 11:50:22 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2005-05-25 19:24:59 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2005-05-27 13:40:49 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-27 13:49:47 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-27 14:00:27 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-27 14:20:04 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-27 15:01:00 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-27 16:49:27 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-27 20:37:59 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-05-31 11:07:53 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-05-31 14:24:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-31 14:53:08 from Greg Stark <gsstark(at)mit(dot)edu>
2005-05-31 15:19:02 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-31 16:02:12 from Greg Stark <gsstark(at)mit(dot)edu>
2005-05-31 16:27:18 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-31 23:19:12 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-06-01 02:36:29 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-06-01 08:50:09 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-06-01 14:05:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-06-01 09:27:41 from "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
2005-06-01 14:07:36 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-05-31 17:58:35 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2005-05-18 07:24:20 from Hannu Krosing <hannu(at)skype(dot)net>
2005-05-18 08:06:22 from Hannu Krosing <hannu(at)skype(dot)net>
2005-05-17 21:23:01 from Hannu Krosing <hannu(at)skype(dot)net>
2005-05-16 18:51:48 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-03-09 08:13:25 from tzirechnoy(at)hotpop(dot)com
2005-03-11 18:31:50 from Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2005-03-13 21:26:13 from Simon Riggs <simon(at)2ndquadrant(dot)com>
Lists:
pgsql-hackers
On Tue, 2005-05-31 at 22:36 -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > Hmmm. I seem to recall asking myself why xl_prev existed if it wasn't
> > used, but passed that by. Damn.
>
> I couldn't believe it'd been overlooked this long, either. It's the
> sort of thing that you assume got done the first time :-(
Guess it shows how infrequently PostgreSQL crashes and recovers.
> > PreAllocXLog was already a reason to have somebody prepare new xlog
> > files ahead of them being used. Surely the right solution here is to
> > have that agent prepare fresh/zeroed files prior to them being required.
>
> Uh, why? That doubles the amount of physical I/O required to maintain
> the WAL, and AFAICS it doesn't really add any safety that we can't get
> in a more intelligent fashion.
OK, I agree that the xl_prev linkage is the more intelligent way to go.
If I/O is a problem, then surely you will agree that PreAllocXLog is
still required and should not be run by a backend? Thats going to show
as a big response time spike for that user.
Thats the last bastion - the other changes are gonna smooth response
times right down, so can we do something with PreAllocXLog too?
Best Regards, Simon Riggs
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