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Re: First steps with 8.3 and autovacuum launcher

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: First steps with 8.3 and autovacuum launcher
Date: 2007-10-02 15:17:47
Message-ID: 14690.1191338267@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Tom Lane escribi:
>> It might be possible to solve this if we reduce the strength of the lock
>> used for ALTER TABLE.  We'd have to go through all the commands
>> potentially issued by a pg_dump script and see if they could all be made
>> to run concurrently with autovac, which is a bit nervous-making but
>> might be feasible; and I'm afraid tablecmds.c would need some
>> restructuring to not use the same lock type for every variant of ALTER.
>> But it seems like a path worth investigating.

> Right.  Are you going to work on it, or do you want me to propose a
> patch?

If you have time to work on it, please do.  But it seems like you first
need to do some investigation --- the idea may not work at all.

In any case, this would still only fix things for pg_restore, and I
remain concerned that people will gripe about autovacuum blocking
locks.  The idea of kicking autovac off tables remains probably more
interesting in the long run.

			regards, tom lane

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Subject: Re: [HACKERS] Re: pgsql: Fix free space map to correctly track the total amount of FSM
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