> -----Original Message-----
> From: pgsql-hackers-owner@hub.org [mailto:pgsql-hackers-owner@hub.org]On
> Behalf Of Tom Lane
>
> Bruce Momjian <pgman@candle.pha.pa.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