I’m looking for some way to send “events” to all instances of KeyedProcessFunction that are processing some different data type. The events are rather one-time modifications than something I want to keep as broadcast state, so want them to be processed once and be gone. Would it be an abuse to use a BroadcastStream + KeyedBroadcastProcessFunction for that? Is it correct to assume that if the KeyedBroadcastProcessFunction doesn’t store them in the broadcast state they’ll be discarded once they processBroadcastElement for each key?

If you don’t store things in broadcast state, then I think stuff will just get thrown away after processing. You are free to use internally as you please

The problem is I don’t know the keys in the events

I’m doing that in one place because I only want some events to go to a subset of the processors

That would be even better, but I can’t get the keys in the events stream (without maintaining a separate state/mapping just for that, which might be doable with queriable state, but probably isn’t great idea). The volume of events is expected to be negligible compared to the main stream of data, so I think broadcasting to all instances should be fine