From:
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc:
Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>,Manfred Koizar <mkoi-pg(at)aon(dot)at>,David Blasby <dblasby(at)refractions(dot)net>, pgsql-hackers(at)postgresql(dot)org
Subject:
Re: Nested transactions and tuple header info
Date:
2004-06-02 16:23:37
Message-ID:
200406021623.i52GNbR29250@candle.pha.pa.us (view raw or flat )
Thread:
2004-05-26 21:00:47 from David Blasby <dblasby(at)refractions(dot)net>
2004-05-26 21:17:08 from Gaetano Mendola <mendola(at)bigfoot(dot)com>
2004-05-26 21:55:27 from David Blasby <dblasby(at)refractions(dot)net>
2004-05-26 22:28:25 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-26 23:02:42 from David Blasby <dblasby(at)refractions(dot)net>
2004-05-27 02:21:19 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-27 03:55:15 from Paul Ramsey <pramsey(at)refractions(dot)net>
2004-05-27 16:26:54 from David Blasby <dblasby(at)refractions(dot)net>
2004-05-26 23:26:20 from pgsql(at)mohawksoft(dot)com
2004-05-26 22:17:55 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-27 01:36:33 from Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
2004-05-27 02:06:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-27 06:13:23 from Dennis Bjorklund <db(at)zigo(dot)dhs(dot)org>
2004-05-27 13:29:46 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-27 18:07:31 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2004-05-27 18:23:07 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-27 19:52:30 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2004-05-27 20:50:24 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-05-28 18:29:51 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2004-05-28 18:47:01 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-28 19:05:42 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-05-28 19:19:29 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-28 19:36:15 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-05-28 19:48:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-28 20:03:19 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-05-28 20:45:28 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-05-29 01:16:33 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-05-29 01:59:53 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-01 12:37:37 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
2004-06-01 12:53:50 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-01 22:40:07 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-01 22:55:39 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-01 23:28:59 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-02 03:17:40 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 03:44:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-02 03:50:13 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 03:50:42 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-02 03:59:14 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 13:52:28 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-02 14:03:15 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-02 14:22:28 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-02 14:47:04 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 14:53:47 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-02 14:57:05 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 15:12:31 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-02 15:47:33 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-02 16:23:37 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 16:46:37 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-02 16:53:55 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-03 20:21:06 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-03 21:08:42 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-02 14:44:07 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-11 07:07:58 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-13 06:32:38 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-13 17:22:05 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2004-06-13 22:02:16 from Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
2004-06-13 14:09:30 from Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
2004-06-01 12:39:13 from Manfred Koizar <mkoi-pg(at)aon(dot)at>
Lists:
pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > I don't understand why a single counter is needed for phantom xids. We
> > keep the cmin/cmax on the tuple already, and our own backend can look up
> > the xmin/xmax that goes with the phantom.
>
> Oh, so you're thinking of an internal table that provides a mapping back
> to the replaced xmin? Ugh. Perhaps it could be made to work, but it's
> a lot of mechanism, and it will slow down visibility checks (since
> AFAICS you'd have to check every subxid against the phantoms table).
My idea was to have a tuple bit indicating the xid is a phantom.
> If we go with a global CID counter then we don't have to add that step.
Seems Alvaro is already using a global counter.
> A global CID counter would also simplify other visibility tests. Alvaro
> hasn't said anything about how he's doing visibility checks across
> different subxacts of the same main xact, but without global CID there
> would need to be some pretty ugly checks to determine whether a subxact
> happened before or after the CID cutoff your outer xact is interested
> in.
If a global counter will reduce the number of phantom checks, then good.
However, I assume Alvaro has to access the creation/expire xid to
determine if the subtransaction committed, so I didn't think a global
counter would help reduce the number of lookups.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
In response to
Responses
pgsql-hackers by date
Next :From: Alvaro HerreraDate: 2004-06-02 16:46:37Subject : Re: Nested transactions and tuple header infoPrevious :From : Alvaro HerreraDate : 2004-06-02 15:47:33Subject : Re: Nested transactions and tuple header info
