Postgres LISTEN/NOTIFY does not scale

Postgres LISTEN/NOTIFY was a consistent pain point for Oban (background job processing framework for Elixir) for a while. The payload size limitations and connection pooler issues alone would cause subtle breakage.

It was particularly ironic because Elixir has a fantastic distribution and pubsub story thanks to distributed Erlang. That’s much more commonly used in apps now compared to 5 or so years ago when 40-50% of apps didn’t weren’t clustered. Thanks to the rise of platforms like Fly that made it easier, and the decline of Heroku that made it nearly impossible.

I didn’t realize Oban didn’t use Mnesia (Erlang built-in).

Very very few applications use mnsesia. There’s absolutely no way I would recommend it over Postgres.