Re: Default autovacuum settings too conservative

On Mon, Feb 06, 2006 at 10:14:53PM -0800, Christopher Browne wrote:
> > On Wed, Feb 01, 2006 at 04:37:07PM -0500, Matthew T. O'Connor wrote:
> >> I think the default settings should be designed to minimize the impact
> >> autovacuum has on the system while preventing the system from ever
> >> getting wildly bloated (also protect xid wraparound, but that doesn't
> >> have anything to do with the thresholds).
> >
> > I don't really see the logic behind that. Problems caused by inadequate
> > vacuuming seem to be much more prevalent than problems caused by vacuum
> > impacting the system. If vacuum impact is a concern I think it more
> > reasonable to make the default vacuum_cost_delay non-zero instead.
>
> That's a good point.
>
> I would not be keen, on the other hand, on having the delays terribly
> high.
>
> Big tables, if delayed significantly, will take plenty longer to
> vacuum, and I always get paranoid about long running transactions :-).

Very true, but I'd hope anyone running a table large enough for this to
make a difference would have done some tuning of their own...

What we really need is a replacement for vacuum_delay that takes
PostgreSQL generated IO activity into account...
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461