Re: changeset generation v5-01 - Patches & git tree

Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> I'm looking at the combined patches 0003-0005, which are essentially all
> about adding a function to obtain relation OID from (tablespace,
> filenode). It takes care to look through the relation mapper, and uses
> a new syscache underneath for performance.

> One question about this patch, originally, was about the usage of
> that relfilenode syscache. It is questionable because it would be the
> only syscache to apply on top of a non-unique index.

... which, I assume, is on top of a pg_class index that doesn't exist
today. Exactly what is the argument that says performance of this
function is sufficiently critical to justify adding both the maintenance
overhead of a new pg_class index, *and* a broken-by-design syscache?

Lose the cache and this probably gets a lot easier to justify. As is,
I think I'd vote to reject altogether.

regards, tom lane