Andres Freund <andres@2ndquadrant.com> writes:
> On 2014-03-13 11:26:10 -0400, Robert Haas wrote:
>> I have however had the thought before that it would be nice to allow
>> for callbacks of invalidation functions of some kind even on catalogs
>> that don't have catcaches.
> Unfortunately the format catcache invalidations have is pretty tightly
> tied to the hash function catcaches use internally. And we need
> something that can be included in the WAL, otherwise it won't work on HS
> nodes.
Note that the existence of a cache doesn't mean it's necessarily
populated. In this example, a catcache on pg_seclabels could be used just
fine, as long as it wasn't used to load labels for large objects. Even if
it were never used at all, it would still provide a usable conduit for
invalidation events.
regards, tom lane