Re: Why our counters need to be time-based WAS: WIP: cross column correlation ...
From:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To:
Robert Haas <robertmhaas(at)gmail(dot)com>
Cc:
Josh Berkus <josh(at)agliodbs(dot)com>,
pgsql-hackers Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject:
Re: Why our counters need to be time-based WAS: WIP: cross column correlation ...
Date:
2011-02-28 19:31:53
Message-ID:
28234.1298921513@sss.pgh.pa.us (view raw or flat )
Thread:
2011-02-22 19:48:47 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 01:58:00 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 02:43:59 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-23 02:56:37 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 03:04:12 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-23 08:15:39 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 14:48:13 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 14:54:11 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 22:37:39 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-23 05:50:50 from Nathan Boley <npboley(at)gmail(dot)com>
2011-02-23 14:46:34 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 14:56:59 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 08:02:28 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 15:10:07 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 22:40:00 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-24 20:42:39 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-25 06:33:59 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-25 13:18:40 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-25 16:45:43 from Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>
2011-02-25 17:50:51 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-25 22:35:45 from Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>
2011-02-25 17:03:58 from Rod Taylor <rod(dot)taylor(at)gmail(dot)com>
2011-02-25 19:26:10 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2011-02-26 05:24:26 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 18:44:08 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2011-03-01 00:18:43 from Rod Taylor <rod(dot)taylor(at)gmail(dot)com>
2011-02-26 13:38:31 from Rod Taylor <rod(dot)taylor(at)gmail(dot)com>
2011-02-27 07:59:44 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-25 23:41:09 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-26 05:29:14 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-26 06:57:54 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-26 14:46:55 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-27 08:03:10 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-27 17:44:35 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-27 22:17:49 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 15:13:39 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 18:04:54 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 18:19:46 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2011-02-28 18:24:13 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 18:31:29 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 18:50:03 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-28 18:54:23 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 19:31:53 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-28 19:37:23 from Michael Glaesemann <grzm(at)seespotcode(dot)net>
2011-02-28 19:39:19 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 19:47:23 from "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
2011-02-28 20:02:30 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-03-02 12:29:59 from Bernd Helmle <mailings(at)oopsware(dot)de>
2011-02-28 20:24:41 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-03-01 08:50:25 from Dimitri Fontaine <dimitri(at)2ndQuadrant(dot)fr>
2011-02-28 19:47:22 from Euler Taveira de Oliveira <euler(at)timbira(dot)com>
2011-02-28 20:03:33 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-28 21:13:47 from Greg Stark <gsstark(at)mit(dot)edu>
2011-02-28 22:05:08 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 22:52:00 from Chris Browne <cbbrowne(at)acm(dot)org>
2011-02-28 22:35:28 from Robert Treat <rob(at)xzilla(dot)net>
2011-02-26 09:33:14 from Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl>
2011-02-26 14:45:24 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-26 18:12:42 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-26 18:44:52 from Greg Stark <gsstark(at)mit(dot)edu>
2011-02-26 18:58:20 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2011-02-26 20:10:46 from Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl>
2011-02-27 08:01:18 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-27 17:24:43 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-24 01:09:10 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-24 03:11:11 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-24 03:30:08 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-24 03:58:08 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-24 15:07:35 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-24 06:13:36 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
Lists:
pgsql-hackers
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Mon, Feb 28, 2011 at 1:50 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Ultimately we need to think of a reporting mechanism that's a bit
>> smarter than "rewrite the whole file for any update" ...
> Well, we have these things called "tables". Any chance of using those?
Having the stats collector write tables would violate the classical form
of the heisenberg principle (thou shalt avoid having thy measurement
tools affect that which is measured), not to mention assorted practical
problems like not wanting the stats collector to take locks or run
transactions.
The ideal solution would likely be for the stats collector to expose its
data structures as shared memory, but I don't think we get to do that
under SysV shmem --- it doesn't like variable-size shmem much. Maybe
that's another argument for looking harder into mmap or POSIX shmem,
although it's not clear to me how well either of those fixes that.
regards, tom lane
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