From:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To:
Joachim Wieland <joe(at)mcknight(dot)de>
Cc:
Simon Riggs <simon(at)2ndquadrant(dot)com>,
Alvaro Herrera <alvherre(at)commandprompt(dot)com>,
Jeff Davis <pgsql(at)j-davis(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>,
Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>,
"Florian G(dot) Pflug" <fgp(at)phlo(dot)org>, Josh Berkus <josh(at)agliodbs(dot)com>,
pgsql-hackers(at)postgresql(dot)org,
Arnaud Betremieux <arnaud(dot)betremieux(at)keyconsulting(dot)fr>
Subject:
Re: Listen / Notify - what to do when the queue is full
Date:
2010-02-15 20:00:16
Message-ID:
12254.1266264016@sss.pgh.pa.us (view raw or flat )
Thread:
2009-11-15 18:19:39 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-16 14:14:58 from Merlin Moncure <mmoncure(at)gmail(dot)com>
2009-11-18 23:59:42 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-19 00:48:17 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 01:06:53 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-19 02:49:21 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 01:26:37 from Josh Berkus <josh(at)agliodbs(dot)com>
2009-11-19 02:08:43 from Andrew Chernow <ac(at)esilo(dot)com>
2009-11-19 03:14:03 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 03:32:14 from Andrew Chernow <ac(at)esilo(dot)com>
2009-11-19 03:43:58 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 04:03:28 from Andrew Chernow <ac(at)esilo(dot)com>
2009-11-19 04:12:33 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 03:12:18 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 12:51:58 from Andreas 'ads' Scherbaum <adsmail(at)wars-nicht(dot)de>
2009-11-19 13:23:57 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-19 16:18:48 from Andreas 'ads' Scherbaum <adsmail(at)wars-nicht(dot)de>
2009-11-19 13:16:28 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-19 14:35:56 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2009-11-19 14:51:14 from "Florian G(dot) Pflug" <fgp(at)phlo(dot)org>
2009-11-19 16:01:06 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2009-11-19 16:17:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 16:37:50 from "Florian G(dot) Pflug" <fgp(at)phlo(dot)org>
2009-11-19 16:41:52 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 17:43:17 from "Florian G(dot) Pflug" <fgp(at)phlo(dot)org>
2009-11-19 17:55:53 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2009-11-19 22:04:07 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-20 06:51:03 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2009-11-20 08:34:16 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-20 09:48:44 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2009-11-20 09:35:46 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-11-20 11:34:08 from Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
2009-11-30 05:15:07 from Jeff Davis <pgsql(at)j-davis(dot)com>
2009-11-30 13:14:17 from Joachim Wieland <joe(at)mcknight(dot)de>
2009-12-04 06:17:40 from Jeff Davis <pgsql(at)j-davis(dot)com>
2009-12-07 04:38:43 from Greg Smith <greg(at)2ndquadrant(dot)com>
2009-12-09 10:43:19 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-07 18:40:54 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-01-07 19:04:28 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-08 12:48:01 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-08 18:19:31 from Merlin Moncure <mmoncure(at)gmail(dot)com>
2010-01-08 18:24:09 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
2010-01-08 20:07:25 from Andrew Chernow <ac(at)esilo(dot)com>
2010-01-08 20:11:38 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
2010-01-08 18:24:45 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-08 20:04:09 from Merlin Moncure <mmoncure(at)gmail(dot)com>
2010-01-08 21:10:27 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-08 21:23:11 from Merlin Moncure <mmoncure(at)gmail(dot)com>
2010-01-11 04:05:55 from "Greg Sabino Mullane" <greg(at)turnstep(dot)com>
2010-01-11 06:58:19 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2010-01-11 10:05:45 from Arnaud Betremieux <arnaud(dot)betremieux(at)keyconsulting(dot)fr>
2010-01-11 13:25:57 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-11 13:51:24 from Merlin Moncure <mmoncure(at)gmail(dot)com>
2010-01-11 14:08:03 from Arnaud Betremieux <arnaud(dot)betremieux(at)keyconsulting(dot)fr>
2010-01-11 13:34:26 from Andrew Chernow <ac(at)esilo(dot)com>
2010-01-19 07:08:45 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-19 09:58:33 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-19 10:54:08 from Arnaud Betremieux <arnaud(dot)betremieux(at)keyconsulting(dot)fr>
2010-01-19 23:41:29 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-20 00:05:07 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-20 00:19:21 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-20 00:24:19 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-20 00:29:03 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-21 02:06:57 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-21 09:14:57 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-21 17:21:56 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-21 23:07:55 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-29 23:02:23 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-02 23:10:23 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-03 01:05:08 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-03 09:34:07 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-07 05:18:25 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-02-07 06:44:39 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-07 16:32:12 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-08 16:16:32 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2010-02-10 23:52:18 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-14 13:46:23 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-14 16:22:12 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-14 17:41:39 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-14 18:47:41 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-14 22:44:42 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-15 11:59:43 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-15 12:45:26 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-15 12:48:26 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-15 19:21:23 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-15 20:00:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-18 17:58:41 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2010-02-18 18:11:08 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-02-18 18:12:14 from Merlin Moncure <mmoncure(at)gmail(dot)com>
2010-02-18 18:46:41 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-16 16:02:52 from "Greg Sabino Mullane" <greg(at)turnstep(dot)com>
2010-02-16 18:22:00 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-15 21:36:55 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-17 05:24:41 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-16 22:41:23 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-17 10:16:39 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-02-17 15:33:45 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-09 06:13:39 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-09 21:46:53 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-09 21:51:05 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-09 22:30:29 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-02-09 23:01:14 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-10 00:02:31 from Andrew Chernow <ac(at)esilo(dot)com>
2010-02-10 00:30:35 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-02-10 00:56:40 from Andrew Dunstan <andrew(at)dunslane(dot)net>
2010-02-10 01:22:50 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-02-10 01:32:14 from Andrew Dunstan <andrew(at)dunslane(dot)net>
2010-02-10 01:38:29 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2010-02-10 01:41:14 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-20 08:25:40 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-20 16:14:23 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-20 20:44:02 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-20 20:54:40 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-01-20 22:08:37 from Jeff Davis <pgsql(at)j-davis(dot)com>
2010-01-20 22:39:01 from Joachim Wieland <joe(at)mcknight(dot)de>
2010-01-20 22:40:26 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-11-19 13:58:59 from "Greg Sabino Mullane" <greg(at)turnstep(dot)com>
2009-11-19 20:39:19 from Chris Browne <cbbrowne(at)acm(dot)org>
Lists:
pgsql-hackers
Joachim Wieland <joe(at)mcknight(dot)de> writes:
> We could probably fake this on the Hot Standby in the following way:
> We introduce a commit record for every notifying transaction and write
> it into the queue itself. So right before writing anything else, we
> write an entry which informs readers that the following records are
> not yet committed. Then we write the actual notifications and commit.
> In post-commit we return back to the commit record and flip its
> status.
This doesn't seem likely to work --- it essentially makes commit non
atomic. There has to be one and only one authoritative reference as
to whether transaction X committed.
I think that having HS slave sessions issue notifies is a fairly silly
idea anyway. They can't write the database, so exactly what condition
are they going to be notifying others about?
What *would* be useful is for HS slaves to be able to listen for notify
messages issued by writing sessions on the master. This patch gets rid
of the need for LISTEN to change on-disk state, so in principle we can
do it. The only bit we seem to lack is WAL transmission of the messages
(plus of course synchronization in case a slave session is too slow
about picking up messages). Definitely a 9.1 project at this point
though.
regards, tom lane
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