Re: [9.2] Confusion over CacheRegisterSyscacheCallback

On Tue, Mar 06, 2012 at 11:10:38AM -0500, Tom Lane wrote:
> Marko Kreen <markokr@gmail.com> writes:
> > So my question is that after doing generic SearchSysCache() like:
> 
> >    tup = SearchSysCache(USERMAPPINGUSERSERVER,
> >         ObjectIdGetDatum(user_mapping->userid),
> >         ObjectIdGetDatum(foreign_server->serverid),
> >         0, 0);
> 
> > what is the proper way to calculate the hashValue that 
> > will be given to callback?
> 
> 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.

-- 
marko