I’d recommend checking out materialize.io for anyone who still has hopes for a reactive db. Is the only project I’ve seen with the ambition of rethink (besides ksqldb, which feels too caveat-ridden, although still interesting).
(Yes, rethink is still “alive”, but between the performance issues and death of the supporting company it’s probably not the wisest piece of tech to become wedded to)
Does materialize.io have a trigger system yet though? One of the great things about Rethink was that client libraries made it easy to have application code stream live changes over websocket etc. to a client.
Yes, we do! It's a little non-standard SQL syntax we added called TAIL. You write TAIL <viewname>, and you get changes pushed to you. You can see a video of me badly explaining it in [2]. You can also do the thing where you create a Kafka SINK of a view and have the system push this to Kafka rather than have a long-running open SQL connection. There's some fun stuff with TAIL AS OF (start the changes at a specific point in time) and TAIL WITH SNAPSHOT (run a SELECT query, and then begin the change stream transactionally with the time of that SELECT query) that you can read about in the docs[1].
(Yes, rethink is still “alive”, but between the performance issues and death of the supporting company it’s probably not the wisest piece of tech to become wedded to)