Hi Till, The session I am dealing with does not have a reliable "end-of-session" event. It could stop sending events all of sudden or it could keep sending events forever. I need to be able to determine when a session expire due to inactivity or to kill off a session if it lives longer than it should. Therefore I need to perform incremental aggregation.
If I can assume ascending timestamp for the incoming events, would there be a workaround? Thanks, Jack On Wed, Aug 17, 2016 at 2:17 AM, Till Rohrmann <trohrm...@apache.org> wrote: > Hi Jack, > > the problem with session windows and a fold operation, which is an > incremental operation, is that you don't have a way to combine partial > folds when merigng windows. As a workaround you have to specify a window > function where you get an iterator over all your window elements and then > perform the fold manually in the window function. > > Cheers, > Till > > On Wed, Aug 17, 2016 at 3:21 AM, Jack Huang <jackhu...@mz.com> wrote: > >> Hi all, >> >> I want to window a series of events using SessionWindow and use fold >> function to incrementally aggregate the result. >> >> events >> .keyBy(_.id) >> .window(EventTimeSessionWindows.withGap(Time.minutes(1))) >> .fold(new Session)(eventFolder) >> >> >> However I get >> >> java.lang.UnsupportedOperationException: Fold cannot be used with a merging >> WindowAssigner. >> >> >> >> Does anyone have a workaround? >> >> >> >> Thanks, >> Jack >> >> >> >> >
