Re: Quick question regarding tablespaces

On Thu, 1 Jul 2004, Mike Rylander wrote:

> On Thursday 01 July 2004 06:43 pm, Gavin Sherry wrote:
> > Hi Mike,
> >
> > In this release, unfortunately not.
>
> That't too bad, but it's not that urgent I suppose.
>
> >
> > I had some idea early on of putting rand_page_cost in pg_tablespace and
> > having the planner have access to it for costing. I didn't actually get
> > around to it but. :-(
>
> Well, I haven't looked at the PG source before, but if you have some specific
> design ideas I would be glad to help out. I'm just not sure where (or when,
> with the official release coming (sort of) soon) to start, but with some
> pointers I'll do what I can!

Well, it wont be in 7.5. Feel free to start looking at how
random_page_cost in cost_index(). It might be worthwhile introducing a per
tablespace performance factor so that we could could say that the cost of
fetching an index tuple from tablespace A is half that of fetching an
index tuple from tablespace B. That idea might not actually turn out to be
a very good one once I look at it closely though.

Gavin