Vivek Khera <vivek@khera.org> writes:
> I have a lot of processing that could benefit from this type of
> synchronization, except the fact that there's no Pg command to "wait
> until I get a notify message".
This is a client library deficiency, not a problem with the backend or
the protocol. In libpq it is actually possible to do it, but you have
to select() or poll() on the socket for yourself, which is a tad ugly.
OTOH, most apps that want to do that also want to wait on other sockets
at the same time, so a cleaner-looking API wouldn't necessarily be any
more useful.
regards, tom lane