The problem isn't on the server; the server already knows how to cancel things, and already supports cancellation over TLS. It's just that psql doesn't use it,

The problem isn't on the server; the server already knows how to cancel things, and already supports cancellation over TLS. It's just that psql doesn't use it, due to the need for a refactor to make that work. Other psql-like frontends do already use it, as the article points out.