Have you seen PipelineDB? It's Postgres, but with something called "continuous views", which are like regular views except they're cached and updated on writes, not re-calculated each time they're read. Sounds like one could use plain tables as the "event log", and these views as the up-to-date cache. And aggregation queries work too, so your regular table can be more than just a cache.

I'm not affiliated, not even a user, it just sounded interesting when it was submitted here.