From:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To:
Bruce Momjian <pgman(at)candle(dot)pha(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:
2004-06-01 23:28:59
Message-ID:
17693.1086132539@sss.pgh.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
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> BEGIN; xid=1
> INSERT a;
> BEGIN; xid=2
> INSERT b;
> DELETE a; xid=3
> COMMIT;
> COMMIT;
> When "DELETE a" happens, we remove the xmin=1 from the tuple header and
> replace it with xmin=3.
You can't change xmin --- this would break visibility tests. Consider
a cursor opened in the outer transaction after the INSERT a. It should
be able to see the "a" row (note that this depends on recognizing xid
equality and then comparing cid's within the outer transaction). If the
subtransaction mangles xmin then it is no longer possible to make this
test correctly.
This is exactly the same argument as not being able to overwrite cmin.
regards, tom lane
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