This is an external pool, rather than an internal one. That is to say that it runs as a separate process that re-implements the Postgres network protocol to acc

This is an external pool, rather than an internal one. That is to say that it runs as a separate process that re-implements the Postgres network protocol to accept incoming connections. The use-case is that it allows you to share one pool across multiple application processes. Depending on your architecture, it can actually make sense to use both an internal pool to reduce connection startup latency and an external pool to reduce your total number of connections.