Andy Colson <andy@squeakycode.net> writes:
> This patch:
> https://commitfest.postgresql.org/action/patch_view?id=597
> caches the cache because, I guess, the cache is slow.
> Simon asked, "What is making the first cache so slow?". Pavel does not know, nor how to fix it, and nobody else
responded.
Well, the cache doesn't need to be "slow" to make it worthwhile to
eliminate repeated cache lookups altogether. We do that in many places.
The questions that need to be asked here are whether the speed gain is
worthwhile, whether there is any possibility of the locally cached
information becoming obsolete, whether it's done in a clean fashion,
whether it should be done somewhere else instead of right here.
regards, tom lane