Hi Dominik, To only fire when new elements have arrived, you should modify your EventTimeTriggerWithEarlyAndLateFiring to detect that more elements have arrived since the last firing.
To do so, you should add some extra of state, e.g. ValueStateDescriptor<Boolean>, that you set to true in the onElement(), and you reset back to false whenever a method (any of the on* methods) returns TriggerResult.FIRE. Given this change, the decision to fire or not should be based on the same criteria as before, plus that the newly introduced state is true (meaning you have new data since the last time you fired). Now for making a trigger with early and late firings part of the main Flink distribution, this is already close to being part of the master branch, as there is already an open pull request. For more you can follow the discussion on the TriggerDSL in the dev mailing list and here: https://cwiki.apache.org/confluence/display/FLINK/FLIP-9%3A+Trigger+DSL <https://cwiki.apache.org/confluence/display/FLINK/FLIP-9:+Trigger+DSL> Thanks, Kostas > On Oct 4, 2016, at 2:54 PM, Dominik Bruhn <domi...@dbruhn.de> wrote: > > Hi, > I'm heavily relying on TimeWindows for my real time processing. Roughly my > job consumes from an AMQP queue, computes some time buckets and saves the > time-buckets to Cassandra. > > I found the EventTimeTriggerWithEarlyAndLateFiring [1] class which already > helped me a lot: Even with long time-windows, I can get intermediate values > already saved to Cassandra by using the earlyFiring (and setting > "accumulating" to true. > > My question is: Would it be possible to only write fire the trigger if the > value of the TimeBucket has changed? What I actually want is only writing to > Cassandra if there is actually something different in the time bucket. > > And, as a side question: Why is something like the > EventTimeTriggerWithEarlyAndLateFiring not in the default Flink distribution? > It seems very handy. > > [1]: > https://github.com/dataArtisans/beam_comp/blob/master/src/main/java/com/dataartisans/beam_comparison/customTriggers/EventTimeTriggerWithEarlyAndLateFiring.java > > > Thanks, > Dominik
