Re: Automatic free space map filling

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Csaba Nagy <nagy(at)ecircle-ag(dot)com>, "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>, Christopher Browne <cbbrowne(at)acm(dot)org>, postgres hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Automatic free space map filling
Date: 2006-04-28 19:58:16
Message-ID: 200604281958.k3SJwGg07888@candle.pha.pa.us
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Tom Lane wrote:
> Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> > So for you it would certainly help a lot to be able to vacuum the first
> > X pages of the big table, stop, release locks, create new transaction,
> > continue with the next X pages, lather, rinse, repeat.
>
> > This is perfectly doable, it only needs enough motivation from a
> > knowledgeable person.
>
> Bruce and I were discussing this the other day; it'd be pretty easy to
> make plain VACUUM start a fresh transaction immediately after it
> finishes a scan heap/clean indexes/clean heap cycle. The infrastructure
> for this (in particular, session-level locks that won't be lost by
> closing the xact) is all there. You'd have to figure out how often to
> start a new xact ... every cycle is probably too often, at least for
> smaller maintenance_work_mem settings ... but it'd not be hard or
> involve any strange changes in system semantics.

Should this be a TODO? One item of discussion was taht people should
just increase their workmem so the job can be done faster in larger
batches.

--
Bruce Momjian http://candle.pha.pa.us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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