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

On Thu, Jun 27, 2013 at 6:18 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 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.

I already voted that way, and nothing's happened since to change my mind.

--
Robert Haas
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