Re: Vacuum only with 20% old tuples

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: The Hermit Hacker <scrappy(at)hub(dot)org>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Vacuum only with 20% old tuples
Date: 2000-07-12 16:15:53
Message-ID: 200007121615.MAA24913@candle.pha.pa.us
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> On Wed, 12 Jul 2000, Bruce Momjian wrote:
>
> > > > I do not see what your 20% idea has to do with this, though, nor
> > > > why it's a good idea. If I've told the thing to vacuum I think
> > > > it should vacuum. 20% of a big table could be a lot of megabytes,
> > > > and I don't want some arbitrary decision in the code about whether
> > > > I can reclaim that space or not.
> > >
> > > I wouldn't mind seeing some automagic vacuum happen *if* >20% expired
> > > ... but don't understand the limit when I tell it to vacuum either ...
> >
> > I am confused by your comment.
>
> Make the backend reasonably intelligent ... periodically do a scan, as
> you've suggested would be required for your above 20% idea, and if >20%
> are expired records, auto-start a vacuum (settable, of course) ...

Would be good if we could to vacuum without locking. We could find a
table when things are mostly idle, and it then.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026

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