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From Aljoscha Krettek <aljos...@apache.org>
Subject Re: Operation of Windows and Triggers
Date Wed, 20 Apr 2016 16:55:54 GMT
Just to clarify, the state of a Trigger on GlobalWindows is still local to
the key of the element that is in the window(s).

On Wed, 20 Apr 2016 at 18:11 Fabian Hueske <fhueske@gmail.com> wrote:

> Hi Piyush,
>
> that's not trivial to implement. You can only do that with a so-called
> GlobalWindow, i.e., a window which receives all elements of a partition,
> and a custom trigger which has state to decide whether it has triggered the
> first window or not. It won't work with a CountTrigger.
>
> Best, Fabian
>
> 2016-04-20 14:20 GMT+02:00 Piyush Shrivastava <piyushjoy@yahoo.co.in>:
>
>> Hi Fabian,
>>
>> Thanks for the information. I also quickly want to ask that if I
>> implement a custom trigger that fires in one hour for the first time and
>> then every five minutes, what all functions do I need to use?
>> I am considering creating my own trigger referring the code here:
>>
>> https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/triggers/CountTrigger.java
>>
>> What changes do I need to make? Is it even possible to do this?
>>
>> Thanks and Regards,
>> Piyush Shrivastava <piyush@webograffiti.com>
>> [image: WeboGraffiti]
>> http://webograffiti.com
>>
>>
>> On Wednesday, 20 April 2016 4:59 PM, Fabian Hueske <fhueske@gmail.com>
>> wrote:
>>
>>
>> Hi Piyush,
>>
>> if you explicitly set a trigger, the default trigger of the window is
>> replaced.
>> In your example, the time trigger is replaced by the count trigger, i.e.,
>> the window is only evaluated after the 100th element was received.
>>
>> This blog post discusses windows and triggers [1].
>>
>> Best, Fabian
>>
>> [1] http://flink.apache.org/news/2015/12/04/Introducing-windows.html
>>
>> 2016-04-20 13:20 GMT+02:00 Piyush Shrivastava <piyushjoy@yahoo.co.in>:
>>
>> I wanted to know how Windows and Triggers work in Flink. I am creating a
>> time window of 20 seconds and a count trigger of 100.
>>
>> stream.keyBy(0)
>>              .timeWindow(Time.seconds(20))
>>              .trigger(CountTrigger.of(100))
>>
>> In this case, when will my window get triggered? When 20 seconds has
>> passed, 100 messages are passed?
>>
>> Thanks and Regards,
>> Piyush Shrivastava <piyush@webograffiti.com>
>> [image: WeboGraffiti]
>> http://webograffiti.com
>>
>>
>>
>>
>>
>

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