Re: [9.2] Confusion over CacheRegisterSyscacheCallback

Marko Kreen <markokr(at)gmail(dot)com> writes:
> On Tue, Mar 06, 2012 at 11:10:38AM -0500, Tom Lane wrote:
>> Why would you need to know that? The reason the calculation function
>> is static is that there's no apparent need to expose that information
>> outside the syscache subsystem.

> Because I need to invalidate my own internal state that corresponds
> to particular system catalog row?

> In current case (plproxy) I need to invalidate libpq connections
> that are created from particular foreign server entry.

[ shrug... ] You could just flush 'em all, which is what most existing
inval callbacks do. Admittedly a libpq connection is a bit more
expensive than the average bit of invalidatable state, but how often
does pg_foreign_server get updated?

Or you could do like setrefs.c does, and assume you know how to
calculate the hash value for an OID-keyed cache.

regards, tom lane