RE: Vacuum only with 20% old tuples

> -----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