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https://issues.apache.org/jira/browse/FLINK-20190?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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GaryGao updated FLINK-20190:
----------------------------
    External issue URL: https://github.com/apache/flink/pull/14099

> A New Window Trigger that can trigger window operation both by event time 
> interval、event count for DataStream API
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-20190
>                 URL: https://issues.apache.org/jira/browse/FLINK-20190
>             Project: Flink
>          Issue Type: New Feature
>          Components: API / DataStream
>            Reporter: GaryGao
>            Priority: Major
>             Fix For: 1.12.0
>
>
> In production environment, when we are do some window operation, such as 
> window aggregation, using data stream api, developers are always asked to not 
> only trigger the window operation when the watermark pass the max timestamp 
> of window, but also trigger it both by fixed event time interval and fixed 
> count of event.The reason why we want to do this is we are looking forward to 
> get the frequently updated window operation result, other than waiting for a 
> long time until the watermark pass the max timestamp of window.This is very 
> useful in reporting and other BI applications.
> For now the default triggers provided by flink can not close this 
> requirement, so I developed a New Trigger, so called 
> CountAndContinuousEventTimeTrigger, combine ContinuousEventTimeTrigger with 
> CountTrigger to do the above thing.
>  
> To use CountAndContinuousEventTimeTrigger, you should specify two parameters 
> as revealed in it constructor:
> {code:java}
> private CountAndContinuousEventTimeTrigger(Time interval, long 
> maxCount);{code}
>  * Time interval, it means this trigger will continuously fires based on a 
> given time interval, the same as ContinuousEventTimeTrigger.
>  * long maxCount, it means this trigger will fires once the count of elements 
> in a pane reaches the given count, the same as CountTrigger. 
>  



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