Thanks for JING & Kurt's reply. I think we prefer to choose the option (a) that will not take the history data into account.
IMO, if we want to process all the historical data, we have to store the original data, which may be a big overhead to backend. But if we just aggregate after the new added function, may just need a data format transfer. Besides, the business logic we met only need the new aggFunction accumulate with new data. -- Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/
