Our (Estuary; I'm CTO) streaming transformation product handles this quite well, actually: https://docs.estuary.dev/concepts/derivations/ https://docs.estuary.

Our (Estuary; I'm CTO) streaming transformation product handles this quite well, actually: https://docs.estuary.dev/concepts/derivations/ https://docs.estuary.dev/concepts/derivations/ Fully managed, UI and config driven. Write SQLite programs using lambdas that are driven by your source events, in order to join data, do streaming transaction processing, and no doubt lots of other things we haven't thought of.