Re: [HACKERS] unusual performance for vac following 8.2 upgrade

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(at)nasby(dot)net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)