I agree, this should be fixed. Thanks for noticing, Dhruv. Would you mind creating a JIRA for this?
Thank you, Fabian 2018-05-28 8:39 GMT+02:00 Bowen Li <bowenl...@gmail.com>: > Hi Dhruv, > > I can see it's confusing, and it does seem the comment should be improved. > You can find concrete explanation of tumbling window and relative arguments > at https://ci.apache.org/projects/flink/flink-docs- > master/dev/stream/operators/windows.html#tumbling-windows > > Feel free to open a PR with better comment. > > Thanks, > Bowen > > > > On Sun, May 27, 2018 at 12:43 PM, Dhruv Kumar <gargdhru...@gmail.com> > wrote: > >> Hi >> >> I was looking at TumblingProcessingTimeWindows.java >> <https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/assigners/TumblingProcessingTimeWindows.java> >> and >> was a bit confused with the documentation at the start of this class. It >> says the following: >> >> /** >> * A {@link WindowAssigner} that windows elements into windows based on >> the current >> * system time of the machine the operation is running on. Windows cannot >> overlap. >> * >> * <p>For example, in order to window into windows of 1 minute, every 10 >> seconds: >> * <pre> {@code >> * DataStream<Tuple2<String, Integer>> in = ...; >> * KeyedStream<String, Tuple2<String, Integer>> keyed = in.keyBy(...); >> * WindowedStream<Tuple2<String, Integer>, String, TimeWindows> windowed = >> * keyed.window(TumblingProcessingTimeWindows.of(Time.of(1, MINUTES), >> Time.of(10, SECONDS)); >> * } </pre> >> */ >> It says one can have tumbling windows of 1 minute, every 10 seconds. >> Doesn’t this become a sliding window then? The SlidingProcessTimeWindows. >> java >> <https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/assigners/SlidingProcessingTimeWindows.java> >> has >> the exact same documentation with just one tiny change (“Windows can >> possibly overlap”). It seems to me that in the above documentation, the >> second Time argument of 10 seconds is for providing the window offset (as >> confirmed here >> <https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/assigners/TumblingProcessingTimeWindows.java#L92>) >> and not for starting the tumbling window every 10 seconds. >> >> Thanks >> >> >> -------------------------------------------------- >> *Dhruv Kumar* >> PhD Candidate >> Department of Computer Science and Engineering >> University of Minnesota >> www.dhruvkumar.me >> >> >
