Re: High inserts, bulk deletes - autovacuum vs scheduled vacuum

On Thu, Jan 11, 2007 at 12:10:34AM -0300, Alvaro Herrera wrote:
> Jim C. Nasby wrote:
>
> > > Is the best way to do that usually to lower the scale factors? Is it
> > > ever a good approach to lower the scale factor to zero and just set the
> > > thresholds to a pure number of rows? (when setting it for a specific
> > > table)
> >
> > The problem is what happens if autovac goes off and starts vacuuming
> > some large table? While that's going on your queue table is sitting
> > there bloating. If you have a separate cronjob to handle the queue
> > table, it'll stay small, especially in 8.2.
>
> You mean "at least in 8.2". In previous releases, you could vacuum
> that queue table until you were blue on the face, but it would achieve
> nothing because it would consider that the dead tuples were visible to a
> running transaction: that running the vacuum on the large table. This
> is an annoyance that was fixed in 8.2.

True, but in many environments there are other transactions that run
long enough that additional vacuums while a long vacuum was running
would still help.
--
Jim Nasby jim(at)nasby(dot)net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)