Hi David,
Thanks for the quick reply
You are indeed right, "Key based watermarking support" in Flink would be most
useful
I gather this cannot be implemented in Flink as per this mail chain -
http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Maintaining-watermarks-per-key-ins
It sounds like you would like to have something like event-time-based
windowing, but with independent watermarking for every key. An approach
that can work, but it is somewhat cumbersome, is to not use watermarks or
windows, but instead put all of the logic in a KeyedProcessFunction (or
RichFlatMap
