Comment by rickstanley

We tried to use LISTEN/NOTIFY for notification purposes, or rather, a queue in which the order mattered (well, kind of, we were aiming for the best scenario where a customer would not perform a specific task in a matter of milliseconds, because we could afford this expectation), in a .NET application using Npgsql.

The listeners were scattered between replicas, so we took advantage of Advisory Locks (https://news.ycombinator.com/item?id=44490510, and my first point felt validated;

but to this day I'm still unsure. Anyway, since it was a complementary system, it didn't hurt to leave it out, we had another background job that would process the outbox table regardless, but I felt it could/would give something closer to "real time" in our system.