Re: [PERFORM] unusual performance for vac following 8.2 upgrade - Mailing list pgsql-hackers

From Jim C. Nasby
Subject Re: [PERFORM] unusual performance for vac following 8.2 upgrade
Date
Msg-id 20070111211609.GT36267@nasby.net
Whole thread Raw
In response to Re: [PERFORM] unusual performance for vac following 8.2 upgrade  (Alvaro Herrera <alvherre@commandprompt.com>)
List pgsql-hackers
On Thu, Jan 11, 2007 at 04:49:28PM -0300, Alvaro Herrera wrote:
> Tom Lane wrote:
>
> > What I think we need to do about this is
> >
> > (1) fix pgstat_vacuum_tabstats to have non-O(N^2) behavior; I'm thinking
> > of using a hash table for the OIDs instead of a linear list.  Should be
> > a pretty small change; I'll work on it today.
> >
> > (2) Reconsider whether last-vacuum-time should be sent to the collector
> > unconditionally.
>
> (2) seems a perfectly reasonably answer, but ISTM (1) would be good to
> have anyway (at least in HEAD).

Actually, I'd rather see the impact #1 has before adding #2... If #1
means we're good for even someone with 10M relations, I don't see much
point in #2.

BTW, we're now starting to see more users with a large number of
relations, thanks to partitioning. It would probably be wise to expand
test coverage for that case, especially when it comes to performance.
--
Jim Nasby                                            jim@nasby.net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)

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