[jlizzle30]

Something like this:

  subscribe ('SELECT * FROM tableA', callback)

On the initial subscription, 'callback' would be called once for each row in 'tableA', then again when a row is inserted or updated. It would be the same as Firebase in this respect.

[cjbprime]

No, you as the person writing this new database, not you as the user of the API.

[eat_veggies]

Not OP but I would watch for mutations in the subscribed columns, then test the changed rows on the query's constraints and fire an event if it satisfies them.

I'm sure there is a more clever/efficient way of doing this though, and I can't wait to see how he/she implements it.