Re: Caching of frequently used objects

On Wed, Jan 19, 2005 at 17:44:00 +0100,
Yann Michel <yann-postgresql(at)spline(dot)de> wrote:
>
> as there were several questions about increasing performance in dwh
> systems I was looking for some hints about how to "pin" an object to the
> buffer so that they are not aged out due to the space is needed by any
> other process or object. I know that in oracle you can do this by
> defining a seperate buffer cache and to asign an object to that special
> buffer cache. So you could assign objects to one pool and all other

You can't really do this. You could use a ram file system and use
tablespaces to put specified tables in that tablespace. However if
your system goes down, the ram fs goes away and that might not be so
good.

> objects will use the default one. I think even count(*) queries could
> benefit from this buffer-splitting due to indexes might be pinned to
> this buffer pool.

This wouldn't have any special effect on count(*) queries.

> So my question is if there is already any comparable functionality or if
> it is planed. I didn't find any comparable feature or TODO on the list.

The developers seem to feel that having postgres and the os decide
what should be cached based on observed usage is better than having
the DBA do this.