Re: Incomplete freezing when truncating a relation during vacuum

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Noah Misch <noah(at)leadboat(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Incomplete freezing when truncating a relation during vacuum
Date: 2013-12-01 20:38:18
Message-ID: 09263396-0d78-4eb6-99f9-7fe74ea2bbfe@email.android.com
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> schrieb:
>Andres Freund <andres(at)2ndquadrant(dot)com> writes:
>> The VACUUM implementation in 9.3 had several bugs: It removed
>multixact
>> xmax values without regard of the importance of contained xids, it
>did
>> not remove multixacts if the contained xids were too old and it
>relied
>> on hint bits when checking whether a row needed to be frozen which
>might
>> not have been set on replicas.
>
>Uh ... what does the last have to do with it? Surely we don't run
>VACUUM on replicas. Or are you talking about what might happen when
>VACUUM is run on a former replica that's been promoted to master?

Unfortunately not. The problem is that xl_heap_freeze's redo function simply reexecutes heap-freeze-tuple() instead of logging much about each tuple...

Andres

--
Please excuse brevity and formatting - I am writing this on my mobile phone.

Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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