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 > > > >
