Author here. The behavior of notify with respect to transactions is indeed notable, and definitely a great feature that makes them distinct from pub/sub in other systems. Notifies fire only when data is ready after the transaction is committed, and they're also deduplicated based on payload so listeners don't have to react to many of the same message unnecessarily.

That said, NOTIFY isn't really what this post is about. It concerns itself with the other half of listen/notify by describing a "notifier" pattern, one which listens via `LISTEN` statements and distributes them application subcomponents to help maximize economy around the use of Postgres connections.