Caching of frequently used objects

Hi,

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
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.
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.

Regards,
Yann