Re: Hot Standby: Caches and Locks

Simon Riggs <simon@2ndQuadrant.com> writes:
>> We can't augment the commit/abort messages because
>> we must cater for non-transactional invalidations also, plus commit
>> xlrecs are already complex enough. So we log invalidations prior to
>> commit, queue them and then trigger the send at commit (if it
>> happens).

> Augmenting the commit messages seems like the better approach. It allows
> invalidation messages to be fired as they are read off the xlrec. Still
> need the additional message type to handle nontransactional
> invalidation. There are other messages possibly more complex than this
> already.

I guess I hadn't been paying attention, but: adding syscache inval
traffic to WAL seems like a completely horrid idea, both from the
complexity and performance standpoints.  What about using the existing
syscache logic to re-derive inval information from watching the update
operations?
        regards, tom lane