Re: [COMMITTERS] pgsql: Avoid losing track of data for shared tables in pgstats.

Gregory Stark wrote:
> "Alvaro Herrera" <alvherre@commandprompt.com> writes:
> 
> > Gregory Stark wrote:
> >
> > > is it possible it's related to the performance drop immediately
> > > following a vacuum analyze we've been seeing?
> >
> > I don't think so, unless you were counting on pgstats data of shared
> > tables for something.  The optimizer, for one, doesn't, so I doubt it
> > would affect query planning.  And it would only affect you if your
> > queries were using shared tables, which I very much doubt ...
> 
> Does anything use the pgstats data for anything other than presenting feedback
> to users?

Not that I know of.

> Autovacuum uses it to estimate when tables should be vacuumed right?

Yep

> This wouldn't have caused autovacuum to go nuts vacuuming these tables
> would it?  But I doubt even then that it could consume much i/o
> bandwidth.

Yes but keep in mind that these are only the shared tables: pg_database,
pg_authid, pg_shdepend, etc.  Those are not tables that you're going to
use regularly, much less _bloat_ regularly that they need frequent
vacuuming.

Maybe pg_shdepend, because it would be used when creating temp tables.

-- 
Alvaro Herrera                         http://www.flickr.com/photos/alvherre/
"Postgres is bloatware by design: it was built to housePhD theses." (Joey Hellerstein, SIGMOD annual conference 2002)