RE: Vacuum only with 20% old tuples

From: "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: "PostgreSQL-development" <pgsql-hackers(at)postgreSQL(dot)org>
Subject: RE: Vacuum only with 20% old tuples
Date: 2000-07-12 03:10:09
Message-ID: 002401bfebae$afda0100$2801007e@tpf.co.jp
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> -----Original Message-----
> From: pgsql-hackers-owner(at)hub(dot)org [mailto:pgsql-hackers-owner(at)hub(dot)org]On
> Behalf Of Tom Lane
>
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > I suggest that we change vacuum to only move remove tuples if there is
> > more than 20% expired tuples.
>
> > When we do vacuum, we drop all indexes and recreate them.
>
> > This fixes the complaint about vacuum slowness when there are many
> > expired rows in the table. We know this is causes by excessive index
> > updates. It allows indexes to shrink (Jan pointed this out to me.) And
> > it fixes the TOAST problem with TOAST values in indexes.
>
> We can't "drop and recreate" without a solution to the relation
> versioning issue (unless you are prepared to accept a nonfunctional
> database after a failure partway through index rebuild on a system
> table). I think we should do this, but it's not all that simple...
>

Is this topic independent of WAL in the first place ?

Regards.

Hiroshi Inoue

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