From:
"Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To:
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Dunstan <andrew(at)dunslane(dot)net>,simon(at)2ndquadrant(dot)com, kleptog(at)svana(dot)org, gsstark(at)mit(dot)edu,pg(at)rbt(dot)ca, zhouqq(at)cs(dot)toronto(dot)edu, pgsql-hackers(at)postgresql(dot)org
Subject:
Re: [Bizgres-general] WAL bypass for INSERT, UPDATE and
Date:
2006-01-03 21:16:55
Message-ID:
20060103211655.GR82560@pervasive.com (view raw or flat )
Thread:
2005-12-22 14:31:33 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-22 17:12:04 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-22 20:10:54 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-03 13:08:46 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-22 18:37:51 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2005-12-22 18:38:45 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2005-12-22 20:18:26 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2005-12-22 22:13:03 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-22 22:36:25 from Stephen Frost <sfrost(at)snowman(dot)net>
2005-12-23 10:18:43 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-22 23:52:38 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2005-12-23 00:05:10 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2005-12-23 00:29:29 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-23 00:53:04 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2005-12-23 04:31:07 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-24 02:37:42 from Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>
2005-12-24 03:00:39 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-24 03:29:50 from Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>
2005-12-24 03:41:42 from Greg Stark <gsstark(at)mit(dot)edu>
2005-12-24 03:50:57 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2005-12-24 04:06:21 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-24 07:01:17 from Greg Stark <gsstark(at)mit(dot)edu>
2005-12-27 17:07:29 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2005-12-27 22:41:57 from Hannu Krosing <hannu(at)skype(dot)net>
2005-12-28 00:30:12 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-24 04:19:01 from Rod Taylor <pg(at)rbt(dot)ca>
2005-12-24 08:23:42 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2005-12-24 15:16:52 from Greg Stark <gsstark(at)mit(dot)edu>
2005-12-24 15:32:29 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-26 12:03:27 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-26 12:22:12 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2005-12-26 16:00:51 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-27 18:20:29 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2005-12-27 22:47:31 from Hannu Krosing <hannu(at)skype(dot)net>
2005-12-28 08:50:26 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2005-12-29 01:58:14 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-29 03:05:30 from "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
2005-12-29 04:09:21 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-29 13:19:45 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-29 14:35:27 from Rod Taylor <pg(at)rbt(dot)ca>
2005-12-29 15:10:40 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-29 16:12:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-29 16:37:39 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-30 13:09:12 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-30 14:53:33 from "Andrew Dunstan" <andrew(at)dunslane(dot)net>
2005-12-30 14:57:06 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-30 17:39:21 from Andrew Dunstan <andrew(at)dunslane(dot)net>
2005-12-30 17:58:15 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-03 15:58:34 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 16:26:51 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-03 16:43:25 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 16:48:01 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-03 17:08:05 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-03 21:16:55 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 21:20:47 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-03 21:27:50 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 22:38:25 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-03 23:23:54 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-04 01:16:19 from Josh Berkus <josh(at)agliodbs(dot)com>
2006-01-04 04:24:09 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-03 23:10:16 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-30 16:49:59 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-30 19:28:41 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-30 21:14:49 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-30 22:36:24 from Greg Stark <gsstark(at)mit(dot)edu>
2005-12-30 22:46:45 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-30 23:04:33 from Greg Stark <gsstark(at)mit(dot)edu>
2005-12-30 23:09:00 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-30 22:50:21 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-30 22:52:49 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-01 01:02:24 from August Zajonc <augustz(at)augustz(dot)com>
2005-12-31 11:59:44 from "Michael Paesold" <mpaesold(at)gmx(dot)at>
2006-01-03 23:58:09 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-03 22:53:53 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-05 17:22:28 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-04 00:11:55 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-05 17:27:05 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-05 21:56:21 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-02-04 03:29:48 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-02-07 00:07:57 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-02-07 02:08:08 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-02-07 02:24:31 from Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
2006-02-07 04:07:41 from Rick Gigger <rick(at)alpinenetworking(dot)com>
2006-02-07 04:13:59 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-02-07 06:51:13 from Rick Gigger <rick(at)alpinenetworking(dot)com>
2006-02-07 09:40:37 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-02-08 01:44:24 from Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
2006-02-08 02:00:51 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-02-07 02:27:45 from Doug McNaught <doug(at)mcnaught(dot)org>
2005-12-29 16:14:37 from "Andrew Dunstan" <andrew(at)dunslane(dot)net>
2005-12-29 16:05:42 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-29 16:24:28 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-03 15:45:21 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 16:21:37 from Stephen Frost <sfrost(at)snowman(dot)net>
2006-01-03 16:29:02 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-03 16:38:52 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 16:55:15 from Stephen Frost <sfrost(at)snowman(dot)net>
2006-01-03 16:54:01 from Stephen Frost <sfrost(at)snowman(dot)net>
2006-01-03 17:37:32 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-03 18:30:56 from Stephen Frost <sfrost(at)snowman(dot)net>
2005-12-29 17:20:32 from Greg Stark <gsstark(at)mit(dot)edu>
2005-12-29 17:30:49 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2005-12-24 14:18:17 from Simon Riggs <simon(at)2ndquadrant(dot)com>
Lists:
pgsql-hackers
On Tue, Jan 03, 2006 at 12:08:05PM -0500, Bruce Momjian wrote:
> Tom Lane wrote:
> > "Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:
> > > On Tue, Jan 03, 2006 at 11:26:51AM -0500, Tom Lane wrote:
> > >> Such an ALTER would certainly require exclusive lock on the table,
> > >> so I'm not sure that I see much use-case for doing it like that.
> > >> You'd want to do the ALTER and commit so as not to lock other people
> > >> out of the table entirely while doing the bulk data-pushing.
> >
> > > Maybe this just isn't clear, but would EXCLUSIVE block writes from all
> > > other sessions then?
> >
> > I don't think it should (which implies that EXCLUSIVE is a bad name).
>
> Agreed, EXCLUSIVE was used to mean an _exclusive_ writer. The new words
> I proposed were PRESERVE or STABLE.
This seems to seriously limit the usefulness, though. You'll only want
to use EXCLUSIVE/PRESERVE/STABLE when you've got a specific set of DML
to do, that you know you can recover from. But if at the same time some
other part of the system could be doing what it thinks will be ACID DML
to that same table, you're now in trouble.
At a minimum that would need to be clearly spelled out in the docs. I
think it also makes a very strong use-case for exposing table-level
shared locks as well, since that would at least allow other backends to
continue reading from the table.
Idealistically, if EXCLUSIVE/PRESERVE/STABLE does it's thing by only
appending new pages, it would be nice if other backends could continue
performing updates at the same time, assuming there's free space
available elsewhere within the table (and that you'd be able to recover
those logged changes regardless of the non-logged operations). But
that's a pretty lofty goal...
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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