Re: FSM, now without WAL-logging

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Zdenek Kotala <Zdenek(dot)Kotala(at)Sun(dot)COM>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: FSM, now without WAL-logging
Date: 2008-09-24 17:24:59
Message-ID: 48DA77EB.6050205@enterprisedb.com
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Zdenek Kotala wrote:
> Heikki Linnakangas napsal(a):
>> There's one known bug left. If we crash after truncating a relation, and
>> the truncation of the FSM doesn't hit the disk but the truncation of the
>> main fork does, we can end up with an FSM that shows that there's free
>> space on pages that don't exist anymore. The straightforward way to fix
>> that is to put back the WAL-logging of FSM truncations, but given that I
>> just ripped off all the rest of the WAL-logging, does anyone have other
>> ideas?
>
> What's about truncate FSM during WAL replay of main fork truncation record?

That would work, except that there's no WAL record for truncating the
main fork.

I considered adding that, WAL-logging the truncation of the main fork,
in vacuum.c. But it would have to be done for all indexams that use the
FSM as well.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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