From:
Hannu Krosing <hannu(at)skype(dot)net>
To:
Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>, pgsql-hackers(at)postgresql(dot)org
Subject:
Re: Stats collector performance improvement
Date:
2006-01-03 21:42:53
Message-ID:
1136324574.4256.17.camel@localhost.localdomain (view raw or flat )
Thread:
2005-12-12 18:33:27 from "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
2005-12-12 18:50:16 from Michael Fuhr <mike(at)fuhr(dot)org>
2005-12-12 23:01:01 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-13 01:07:51 from Michael Fuhr <mike(at)fuhr(dot)org>
2005-12-13 03:20:45 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-15 23:44:48 from Michael Fuhr <mike(at)fuhr(dot)org>
2005-12-16 00:06:39 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2005-12-16 05:44:58 from Kevin Brown <kevin(at)sysexperts(dot)com>
2005-12-16 13:17:25 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2005-12-17 02:44:19 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-02 18:40:40 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-02 18:45:21 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-02 19:13:47 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-02 20:20:24 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-02 21:03:20 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2006-01-02 21:48:45 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-01-03 09:40:53 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-03 16:35:56 from "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
2006-01-03 23:28:34 from Greg Stark <gsstark(at)mit(dot)edu>
2006-01-03 21:42:53 from Hannu Krosing <hannu(at)skype(dot)net>
2006-01-08 16:49:12 from Greg Stark <gsstark(at)mit(dot)edu>
2006-01-09 15:48:21 from Hannu Krosing <hannu(at)skype(dot)net>
2006-01-02 21:48:15 from Hannu Krosing <hannu(at)skype(dot)net>
2006-01-03 04:06:57 from Jan Wieck <JanWieck(at)Yahoo(dot)com>
2006-01-03 09:54:57 from Simon Riggs <simon(at)2ndquadrant(dot)com>
2006-01-03 16:43:23 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-01-05 00:39:42 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-15 04:05:38 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-15 06:09:43 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2006-06-15 14:27:33 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-06-15 15:57:36 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-15 21:38:01 from Josh Berkus <josh(at)agliodbs(dot)com>
2006-06-15 21:42:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-06-15 21:46:29 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-16 01:34:12 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2006-06-16 01:56:34 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-06-16 03:14:06 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-16 03:27:50 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2006-06-16 03:57:22 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-16 04:48:27 from "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
2006-06-16 16:03:22 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-16 16:12:50 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
2006-06-16 16:24:03 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2006-06-16 18:14:47 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
2006-06-17 17:43:06 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2006-06-15 08:00:27 from "Larry Rosenman" <ler(at)lerctr(dot)org>
2006-06-15 19:58:27 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
2006-06-15 20:29:36 from Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
Lists:
pgsql-hackers pgsql-patches pgsql-performance
Ühel kenal päeval, T, 2006-01-03 kell 09:40, kirjutas Simon Riggs:
> We can also save lots of cycles on the current statement overhead, which
> is currently the worst part of the stats, performance-wise. That
> definitely needs redesign. AFAICS we only ever need to know the SQL
> statement via the stats system if the statement has been running for
> more than a few minutes - the main use case is for an admin to be able
> to diagnose a rogue or hung statement.
Interestingly I use pg_stat_activity view to watch for stuck backends,
"stuck" in the sense that they have not noticed when client want away
and are now waitin the TCP timeout to happen. I query for backends which
have been in "<IDLE>" state for longer than XX seconds. I guess that at
least some kind of indication for this should be available.
Of course this would be much less of a problem if there was a
possibility for sime kind of keepalive system to detect when
client/frontend goes away.
> Pushing the statement to stats
> every time is just a big overhead. That suggests we should either have a
> pull
I could live with "push", where pg_stat_activity would actually ask each
live backend for its "current query". This surely happens less often
than queries are performed (up to few thousand per sec)
-------------
Hannu
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