Re: Autovacuum in the backend

On Fri, 17 Jun 2005, Russell Smith wrote:

> > >4) Related to this, I guess, is that a user's FSM settings might be
> > >completely inappropriate. The 'Just read the manual' or 'Just read the
> > >logs' argument doesn't cut it, because the main argument for autovacuum in
> > >the backend is that people do not and will not.
> > >
> > >
> >
> > Agreed, it doesn't solve all problems, and I'm not arguing that the
> > integration of AV makes PostgreSQL newbie safe it just helps reduce the
> > newbie problem.   Again if the default FSM settings are inappropriate
> > for a database then the user is probably doing something more
> > complicated that a "my cat minka" database and will need to learn some
> > tuning skills anyway.
> >
> > >5) It doesn't actually shrink tables -- ie, there's no VACUUM FULL. If
> > >we're telling users about VACUUM less often than we are now, there's bound
> > >to be bloating issues (see 4).
> > >
> > >
> >
> But what's stopping the implementation of a Partial VACUUM FULL, where we lock the table,
> move enough blocks to shorten the relation so that there is say < 10% bloat, or whatever is
> appropriate for that table.  Or even just short the table a few block, and repeat the process
> when you have some time too.

Its a question of where you start off from again. You cannot just say
'I've vacuumed the first 100 pages' because it could well have changed
underneath you.

Gavin