Union operator best practices: We have 3 streams we want to union. We use keyBy after the union and pass the keyed stream through a tumbling window. Should we key all 3 streams before the union? If so, is the result of the union still keyed? Or do we need to keyBy again?

I'm also curious about this. From what I've read in the docs, it doesn't seem like it would matter. But I bet there's some nuances at play that aren't immediately obvious.

Right, I could not find a whole lot about union in the docs