"A.M." <agentm@themactionfaction.com> writes:
> So, it is impossible to differentiate between a notification with an
> empty string payload and a notification without a payload due to the
> backend protocol defining the payload as a string.
That's correct. This was baked into the FE/BE protocol in 2003;
we're not going to change it now, especially not without a pretty
convincing argument why it's critical functionality to have.
regards, tom lane