Re: Re: Hot Standby query cancellation and Streaming Replication integration
From:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To:
Greg Stark <gsstark(at)mit(dot)edu>
Cc:
Greg Smith <greg(at)2ndquadrant(dot)com>,
PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject:
Re: Re: Hot Standby query cancellation and Streaming Replication integration
Date:
2010-02-26 18:53:16
Message-ID:
1916.1267210396@sss.pgh.pa.us (view raw or flat )
Thread:
2010-02-26 08:33:35 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-26 12:10:07 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-26 18:53:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-26 19:01:30 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-26 19:06:51 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-26 19:16:40 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-26 20:02:08 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-26 20:22:56 from "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
2010-02-26 20:04:23 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-26 20:21:05 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-26 20:10:11 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-26 20:25:33 from Aidan Van Dyk <aidan(at)highrise(dot)ca>
2010-02-26 20:30:01 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-26 21:06:10 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-26 21:11:32 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-26 21:19:39 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-26 21:22:47 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-26 21:44:20 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-27 04:02:24 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-28 21:58:51 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-27 06:53:24 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-26 21:39:12 from Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
2010-02-26 21:48:38 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-26 22:11:28 from Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
2010-02-26 22:20:37 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-27 09:07:32 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-27 09:33:34 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-26 23:56:55 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 00:36:57 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-27 02:43:58 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 03:40:57 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-27 04:38:38 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 04:53:48 from Aidan Van Dyk <aidan(at)highrise(dot)ca>
2010-02-27 05:08:35 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 20:31:06 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-27 22:09:59 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 22:26:22 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-28 02:14:28 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-28 05:28:17 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-28 06:01:49 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-28 06:18:00 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 00:43:48 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-27 01:53:13 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 02:30:56 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-27 03:11:49 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 22:28:49 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-27 23:49:09 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 03:59:41 from "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
2010-02-27 04:31:12 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 14:34:08 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-26 23:33:57 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 00:21:11 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-27 06:59:10 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-27 14:56:51 from Tatsuo Ishii <ishii(at)postgresql(dot)org>
2010-02-28 01:00:52 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-02-28 06:07:20 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-28 13:54:48 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-28 15:56:28 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-28 19:47:38 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-28 20:48:51 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-28 22:38:28 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-01 03:00:09 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-01 17:50:52 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-01 18:26:09 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-01 18:46:29 from Greg Stark <gsstark(at)mit(dot)edu>
2010-03-01 19:21:48 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-01 19:32:24 from Greg Stark <gsstark(at)mit(dot)edu>
2010-03-01 19:35:37 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
2010-03-01 19:43:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-03-01 20:04:41 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-02 01:34:53 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-02 20:57:39 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-03-02 20:58:03 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-03-02 21:36:52 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-02 23:39:10 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-01 03:12:22 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-03-01 22:32:01 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-01 22:52:50 from "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
2010-03-02 00:46:22 from Greg Stark <stark(at)mit(dot)edu>
2010-03-02 01:04:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-03-02 02:08:27 from Aidan Van Dyk <aidan(at)highrise(dot)ca>
2010-03-02 01:50:28 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-03-02 06:21:10 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-02 04:56:45 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-28 20:54:52 from Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
2010-02-28 21:42:00 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-28 20:21:23 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-02 04:54:04 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-02 05:50:08 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-02 18:30:15 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-02 18:34:33 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-02 20:11:00 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-03-02 23:44:16 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-10 06:29:19 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-10 11:38:12 from Greg Stark <gsstark(at)mit(dot)edu>
2010-03-10 18:59:50 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-11 00:51:29 from Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
2010-03-11 01:39:37 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-03-11 05:58:35 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-02 19:03:14 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-03-02 21:00:24 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-26 14:10:26 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-26 14:24:30 from Richard Huxton <dev(at)archonet(dot)com>
2010-02-26 18:47:09 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-27 00:11:36 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 00:54:57 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-27 02:52:12 from Greg Smith <greg(at)2ndquadrant(dot)com>
2010-02-27 02:56:01 from Bruce Momjian <bruce(at)momjian(dot)us>
2010-02-26 14:17:23 from Richard Huxton <dev(at)archonet(dot)com>
2010-02-26 14:45:07 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-26 14:57:16 from Richard Huxton <dev(at)archonet(dot)com>
2010-02-26 15:21:03 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2010-02-26 17:45:33 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-02-26 19:02:12 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-26 16:43:24 from Richard Huxton <dev(at)archonet(dot)com>
2010-02-26 17:46:15 from Greg Stark <gsstark(at)mit(dot)edu>
2010-02-28 22:15:18 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
Lists:
pgsql-hackers
Greg Stark <gsstark(at)mit(dot)edu> writes:
> In the model you describe any long-lived queries on the slave cause
> tables in the master to bloat with dead records.
Yup, same as they would do on the master.
> I think this model is on the roadmap but it's not appropriate for
> everyone and I think one of the benefits of having delayed it is that
> it forces us to get the independent model right before throwing in
> extra complications. It would be too easy to rely on the slave
> feedback as an answer for hard questions about usability if we had it
> and just ignore the question of what to do when it's not the right
> solution for the user.
I'm going to make an unvarnished assertion here. I believe that the
notion of synchronizing the WAL stream against slave queries is
fundamentally wrong and we will never be able to make it work.
The information needed isn't available in the log stream and can't be
made available without very large additions (and consequent performance
penalties). As we start getting actual beta testing we are going to
uncover all sorts of missed cases that are not going to be fixable
without piling additional ugly kluges on top of the ones Simon has
already crammed into the system. Performance and reliability will both
suffer.
I think that what we are going to have to do before we can ship 9.0
is rip all of that stuff out and replace it with the sort of closed-loop
synchronization Greg Smith is pushing. It will probably be several
months before everyone is forced to accept that, which is why 9.0 is
not going to ship this year.
regards, tom lane
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