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From Maximilian Michels <...@apache.org>
Subject Re: ContinuousEventTimeTrigger breaks coGrouped windowed streams?
Date Tue, 22 Nov 2016 10:50:52 GMT
Hi William,

I've reproduced your example locally for some toy data and everything
was working as expected (with the early triggering). So I'm assuming
either there is something wrong with your input data or the behavior
doesn't always manifest.

Here's the example I run in case you want to try:
https://gist.github.com/mxm/6cb1e6e9a572a26df76917176849f405

Gyula is right, the ContinuousEventTimeTrigger never purges the window
but that you can circumvent that by extending this trigger and purging
at the end of the window, similarly as done in the EventTimeTrigger.

-Max


On Mon, Nov 21, 2016 at 6:52 PM, William Saar <william@saar.se> wrote:
> Thanks!
>
> Yes, the SlidingEventTimeWindow works, but is there any way to pre-aggregate
> things with tumbling windows that emit events more often than their window
> size? Perhaps I can do this before I merge the streams? (But if
> ContinuousEventTimeTrigger is the only way to do that, it's bad if it
> doesn't clean up its state).
>
> I assume using sliding window states will be too large and less efficient
> than tumbling windows as a sliding fold needs to keep all events in the
> window and recompute the fold as events slide out of the window, while a
> tumbling fold just needs to keep the aggregation and can discard events as
> it folds them.
>
> I am reviewing how one would replace a batch solution based on 3 bucketed
> aggregations of different window sizes and it seems tumbling windows would
> be a perfect fit and would need to keep only the 3 aggregations a memory,
> while sliding windows would need to keep up to 3 copies of all events (for
> at least the smallest window size) to compute the same type of results.
>
> Hälsningar!
> William
>
>
> ----- Original Message -----
> From:
> user@flink.apache.org
>
> To:
> <user@flink.apache.org>
> Cc:
>
> Sent:
> Mon, 21 Nov 2016 08:22:16 +0000
> Subject:
> Re: ContinuousEventTimeTrigger breaks coGrouped windowed streams?
>
>
>
> Hi William,
>
> I am wondering whether the ContinuousEventTimeTrigger is the best choice
> here (it never cleans up the state as far as I know).
>
> Have you tried the simple SlidingEventTimeWindows as your window function?
>
> Cheers,
> Gyula
>
> William Saar <william@saar.se> ezt írta (időpont: 2016. nov. 19., Szo,
> 18:28):
>>
>> Hi!
>>
>> My topology below seems to work when I comment out all the lines with
>> ContinuousEventTimeTrigger, but prints nothing when the line is in there.
>> Can I coGroup two large time windows that use a different trigger time than
>> the window size? (even if the ContinuousEventTimeTrigger doesn't work for
>> coGroups, I would not expect the result to be completely silent).
>>
>> The streams I'm cogroupng are from 2 different Kafka sources and uses
>> event time with 0 out of orderness and I'm on Flink 1.1.3, if that helps
>>
>> DataStream<CommonType> stream1 =
>>     <stream of event type1>
>>     .window(TumblingEventTimeWindows.of(Time.seconds(30)))
>>     .trigger(ContinuousEventTimeTrigger.of(Time.seconds(10)))
>>     .fold(...);
>>
>>
>> DataStream<CommonType> stream2 =
>>     <stream of event type2>
>>     .window(TumblingEventTimeWindows.of(Time.seconds(30)))
>>     .trigger(ContinuousEventTimeTrigger.of(Time.seconds(10)))
>>     .fold(...);
>>
>>
>>
>> stream1.coGroup(stream2).where(...).equalTo(...)
>>     .window(TumblingEventTimeWindows.of(Time.seconds(30)))
>>     .trigger(ContinuousEventTimeTrigger.of(Time.seconds(10)))
>>     .print()
>>
>> Thanks,
>>
>> William
>>
>

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