From:
Kevin Grittner <kgrittn(at)ymail(dot)com>
To:
Jim Nasby <jim(at)nasby(dot)net>, Christopher Browne <cbbrowne(at)gmail(dot)com>
Cc:
Andres Freund <andres(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,
Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>,
Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>,
Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject:
Re: autovacuum not prioritising for-wraparound tables
Date:
2013-01-30 21:28:36
Message-ID:
1359581316.46973.YahooMailNeo@web162903.mail.bf1.yahoo.com (view raw or flat )
Thread:
2013-01-24 21:57:15 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-24 22:22:50 from Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
2013-01-24 23:25:47 from Christopher Browne <cbbrowne(at)gmail(dot)com>
2013-01-24 23:48:26 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-01-25 15:29:15 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-25 15:49:25 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2013-01-25 15:59:56 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-25 16:44:49 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-01-25 16:51:33 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-01-25 17:00:51 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-25 17:56:46 from Christopher Browne <cbbrowne(at)gmail(dot)com>
2013-01-30 21:05:52 from Jim Nasby <jim(at)nasby(dot)net>
2013-01-30 21:28:36 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-01-30 22:44:34 from Jim Nasby <jim(at)nasby(dot)net>
2013-01-30 22:37:33 from Christopher Browne <cbbrowne(at)gmail(dot)com>
2013-01-30 22:50:22 from Jim Nasby <jim(at)nasby(dot)net>
2013-01-31 19:36:47 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-31 19:40:14 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-31 19:54:31 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-31 20:18:24 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-31 20:28:58 from Christopher Browne <cbbrowne(at)gmail(dot)com>
2013-02-01 21:59:52 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-02-01 22:43:04 from Christopher Browne <cbbrowne(at)gmail(dot)com>
2013-02-01 23:08:21 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-03-21 22:15:47 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-02-02 13:41:35 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-02 16:25:01 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-02-02 18:49:13 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-02 19:54:10 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-02-02 21:03:54 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-03 02:08:34 from Christopher Browne <cbbrowne(at)gmail(dot)com>
2013-02-03 02:47:34 from Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>
2013-02-28 17:21:58 from Jim Nasby <jim(at)nasby(dot)net>
2013-01-31 19:55:06 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-31 19:58:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-01-31 20:07:07 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-01-25 17:19:25 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-25 17:35:25 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-25 17:52:46 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-01-25 18:01:16 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-25 18:02:19 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-25 18:17:20 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-01-25 19:22:50 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-27 19:33:18 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-01-27 09:17:27 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2013-01-27 17:11:53 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-27 21:29:56 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2013-01-27 19:17:24 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-01-29 03:03:19 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-25 00:18:32 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-28 13:11:12 from Josh Berkus <josh(at)agliodbs(dot)com>
2013-01-28 14:10:24 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-28 16:15:29 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-01-28 16:21:15 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-02 04:48:48 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-01-29 05:09:52 from Josh Berkus <josh(at)agliodbs(dot)com>
2013-01-30 09:48:40 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-30 13:39:29 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-01-30 13:58:24 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-30 14:55:21 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-30 18:21:07 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-01-30 18:26:06 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-30 18:26:37 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-02-01 15:17:25 from Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
2013-02-01 22:05:46 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-02-01 22:34:18 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-01 23:09:34 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-02-02 13:25:11 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-03 17:25:37 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-02-03 22:58:43 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-02-04 21:59:57 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-02-04 22:16:02 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-02-02 15:43:43 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-02-03 01:40:04 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-03 01:41:42 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-03 16:17:42 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-02-03 16:41:20 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-02-03 18:26:25 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2013-02-03 21:08:35 from Andres Freund <andres(at)2ndquadrant(dot)com>
2013-01-30 15:58:07 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-01-30 18:31:50 from Kevin Grittner <kgrittn(at)ymail(dot)com>
2013-01-30 15:35:46 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2013-01-31 03:41:38 from Josh Berkus <josh(at)agliodbs(dot)com>
2013-01-29 03:35:22 from Robert Haas <robertmhaas(at)gmail(dot)com>
2013-01-27 20:47:20 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Lists:
pgsql-hackers
Jim Nasby <jim(at)nasby(dot)net> wrote:
> the only reason to freeze is XID wrap
The conclusions you draw seem to be based on a slightly different
premise than stated here; the conclusions are only supported by the
assumption that "the only reason to freeze at any particular moment
is to assure that all tuples are frozen in time to prevent
transaction wraparound." In a mostly write-only database, that has
to happen for nearly every tuple at some point -- but *which* point
is best is not necessarily "as late as possible".
> then the *ideal* time to start a freeze vacuum on a table is so
> that the vacuum would end *exactly* as we were about to hit XID
> wrap.
For a tuple which you know is going to survive long enough to be
frozen, the *ideal* time to freeze a tuple, from a performance
standpoint, is when the tuple is written, to eliminate a separate
WAL-log operation. The *next best* time to freeze is when the hint
bits are set, to avoid a separate page write. If you are doing
differential backups, the *third best* time to freeze is before the
first differential backup of the tuple, to avoid a separate backup
after the freeze. And so on.
-Kevin
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