big +1 on reworking the timestamp extractor. There were too many users stumbling across this. I also misunderstood it when trying it out the first time.
On Tue, Feb 9, 2016 at 4:54 PM, Stephan Ewen <se...@apache.org> wrote: > Hi everyone! > > There are two remaining issues right now pending for 1.0 that will cause > breaking API changes in the Streaming API. > > > 1) > [FLINK-3379] > > The Timestamp Extractor needs to be changed. That really seems necessary, > based on the user feedback, because a lot of people mentioned that they are > getting confused about the TimestampExtractor's mixed two-way system of > generating watermarks. > > The issue suggests to pull the two different modes of generating watermarks > into two different classes. > > > 2) > > [FLINK-3371] makes the "Trigger" an abstract class (currently interface) > and moves the "TriggerResult" to a dedicated class. This is necessary for > avoiding breaking changes in the future, after the release. > > The reason why for these changes are "aligned windows", which have one > Trigger for the entire window across all keys ( > https://issues.apache.org/jira/browse/FLINK-3370) > > Aligned windows are for example most sliding/tumbling time windows, while > unaligned windows (with a trigger per key) are for example session and > count windows. For aligned windows, we can implement an optimized > representation that uses less memory and is more lightweight to checkpoint. > > Also, the Trigger class may evolve a bit, and and with an abstract class we > can add methods without breaking user-defined Triggers in the future. > > > Greetings, > Stephan >
