It's hardly compatible with the existing events architecture and API, so
I'm still somewhat sceptical about its implementation.

 Dmitry

I don't now API details, but my idea: what if we can specify 'mask' in Event name on clients, e.g.  "ORDER_CHANGED*"?

Then client subscribes to event "ORDER_CHANGED*", and his code receive all events, who name is starting with "ORDER_CHANGED".

On DB side in trigger we can fire event like that:

post_event('ORDER_CHANGED' || new.ID)

In client's code he get an actual event name, like ' ORDER_CHANGED9999'. Then he can parse received string as he need.