Re: [HACKERS] Autovacuum loose ends

On Mon, Jul 25, 2005 at 09:31:15AM +0800, Christopher Kings-Lynne wrote:
> >> We have to consider what
> >> happens at stat reset -- AFAICS there's no problem, because as soon as
> >> the table sees some activity, it will be picked up by pgstat.
> >> However, it would be bad if stats are reset right after some heavy
> >> activity on a table. Maybe the only thing we need is documentation.
> >
> >What's the use-case for having the stat reset feature at all?
>
> I believe I was the root cause of the pg_stat_reset() function. The
> idea at the time was that if you decide to do a round of index
> optimisation, you want to be able to search for unused indexes and
> heavily seq. scanned tables.
>
> If you reset the stats you have 'clean' data to work with. For
> instance, you can get 24 hours of clean stats data.

Ok, so there's a reason for having a manual stat-reset. However what's
the rationale for cleaning stats at postmaster start? In fact I think
it's actively bad because you lose any data you had before postmaster
stop/crash.

--
Alvaro Herrera (<alvherre[a]alvh.no-ip.org>)
"I personally became interested in Linux while I was dating an English major
who wouldn't know an operating system if it walked up and bit him."
(Val Henson)