Re: Autovacuum on by default?

Larry Rosenman wrote:
> Jim C. Nasby wrote:
> > On Tue, Aug 22, 2006 at 11:08:49AM -0400, Tom Lane wrote:
> >> "Jim C. Nasby" <jim@nasby.net> writes:
> >>> If there's a bunch of activity on a table but stats are reset
> >>> before a vacuum is run on it and then a vacuum is run, the user
> >>> will still be left thinking that the table needs to be vacuumed.
> >> 
> >> Except that autovac *won't* vacuum it if the stats have been reset.
> >> So I'm not seeing that there's really a problem in practice.
> > 
> > IIRC the stats also include info about regular (manual) vacuums, so
> > the above scenario still applies.
> 
> They do.  The stats patch as applied captures both autovacuum and manual
> vacuum
> as well as analyze (both from the Autovacuum daemon and manual).

But the original point still remains: if you manually VACUUM a table
that does not have a pgstat entry, the pgstat system will drop the
"vacuum timestamp" message on the floor without recreating the entry.

I think there is a reasonable case for saying that a manual vacuum could
hint pgstat to create the entry instead.  On the other hand, if
autovacuum never vacuums a table with no pgstat entry, then you could
just create the pgstat entry in both cases and it would be the same
anyway.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.