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From Dhruv Kumar <gargdhru...@gmail.com>
Subject Re: Clarification in TumblingProcessing TimeWindow Documentation
Date Mon, 28 May 2018 15:30:22 GMT
Sure thanks a lot! Bowen and Fabian. I will create the JIRA and also submit a PR with a better
comment.

--------------------------------------------------
Dhruv Kumar
PhD Candidate
Department of Computer Science and Engineering
University of Minnesota
www.dhruvkumar.me

> On May 28, 2018, at 03:50, Fabian Hueske <fhueske@gmail.com> wrote:
> 
> 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 <bowenli86@gmail.com <mailto:bowenli86@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
<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 <gargdhruv36@gmail.com <mailto:gargdhruv36@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 <http://www.dhruvkumar.me/>
> 
> 


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