Re: database caches

Ruslan A Dautkhanov <rusland(at)scn(dot)ru> writes:
> I have problem in PG performance - all database caches is allocated
> to one table, which is much greater than all other tables together, but
> requests to this huge table much rarely, than requests with
> other tables.

What makes you think that all the cache is allocated for this one
specific table?

Also, caching is done on a page-by-page basis, not per-relation.

> How can I adjust which tables should be cached more (cache rate), and
> which less, if this possible?? Or which tables not to cache
> completely.

The buffer manager decides what to cache by itself; there are a few
knobs you can tweak (shared_buffers, for example), but for the most
part the buffer manager is expected to do its job.

In your specific example, it doesn't sound like there's a need to
manually tweak the buffer manager: the large but infrequently accessed
table will likely not have very many buffers kept in memory.

Cheers,

Neil

--
Neil Conway <neilc(at)samurai(dot)com> || PGP Key ID: DB3C29FC