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Re: Very strange postgresql behaviour

From: Arnau <arnaulist(at)andromeiberica(dot)com>
To: "pgsql-admin(at)postgresql(dot)org" <pgsql-admin(at)postgresql(dot)org>
Subject: Re: Very strange postgresql behaviour
Date: 2007-01-29 18:42:44
Message-ID: 45BE4024.8010506@andromeiberica.com (view raw or flat)
Thread:
Lists: pgsql-admin
Tom Lane wrote:
> Arnau <arnaulist(at)andromeiberica(dot)com> writes:
>>    I have postgresql 7.4.2 running on debian and I have the oddest 
>> postgresql behaviour I've ever seen.
> 
> Is this specific to these two rows?  If so it might be a case of this
> bug, which was repaired in 7.4.13:

   I don't know, we have discovered those two rows but I'm not sure if 
there are more. Is there any way to check it?

> 
> http://archives.postgresql.org/pgsql-general/2006-05/msg00756.php
> http://archives.postgresql.org/pgsql-committers/2006-05/msg00174.php
> 
> 2006-05-19 12:31  tgl
> 
> 	* src/backend/executor/nodeIndexscan.c (REL7_4_STABLE): Fix nasty
> 	bug in nodeIndexscan.c's detection of duplicate tuples during a
> 	multiple (OR'ed) indexscan.  It was checking for duplicate
> 	tuple->t_data->t_ctid, when what it should be checking is
> 	tuple->t_self.	The trouble situation occurs when a live tuple has
> 	t_ctid not pointing to itself, which can happen if an attempted
> 	UPDATE was rolled back.  After a VACUUM, an unrelated tuple could
> 	be installed where the failed update tuple was, leading to one live
> 	tuple's t_ctid pointing to an unrelated tuple.	If one of these
> 	tuples is fetched by an earlier OR'ed indexscan and the other by a
> 	later indexscan, nodeIndexscan.c would incorrectly ignore the
> 	second tuple.  The bug exists in all 7.4.* and 8.0.* versions, but
> 	not in earlier or later branches because this code was only used in
> 	those releases.  Per trouble report from Rafael Martinez Guerrero.
> 
> REINDEX wouldn't fix this, although a table dump and reload would.
> 
> 			regards, tom lane
> 
> PS: please don't spam multiple lists with the same question.

   My intention was not spam mulitple lists, the problem was that I was 
not sure where to post this question.


-- 
Arnau

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