Re: Is there a system of cache in pgsql 7.3rc1 ?

On Thu, 21 Nov 2002, David Pradier wrote:

> Hi!
> This is my first post to the list.
>
> I'm currently searching to improve the performances of some requests,
> and recently switched to postgresql 7.3rc1.
>
> I thought there would be in this release a kind of cache for the results
> of requests (i.e. the second time a request is asked, if the concerned
> tables haven't changed, the result of the request isn't calculated another time, but
> taken from a cache.) ?
> Am i wrong ?
> Does such a mechanism exist ?
> Is it planned to create one ?

This issue has been discussed. The performance gains from a results cache
are not all that great, and postgresql's mvcc "locking" mechanism isn't a
good candidate to be served by results caching / updating. Generally
speaking, if you've got enough memory in your box, then the results are
"cached" in memory, requiring only sorting before being output.

This is a niche problem that is not likely to be implemented any time
soon.