Earlier quoted context omitted.
It's using Postgres pg_notify to subscribe to tables and using a WebSocket server to distribute the changes. The table watcher is written in Haskell and based on the IHP haskell framework. Using Haskell makes it very easy and efficient to deal with lot's of active sessions in parallel. You can find the source code here https://github.com/digitallyinduced/ihp/blob/master/IHP/Data... if you're interested :)
That's a similar approach to supabase. Why reinvent the wheel? (I'm asking out of curiosity here). Why websockets? Do you allow bidirectional communication? If not, wouldn't it be better to use http push for easier scaling?
Supabase is a copy of Firebase. Same question?