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https://issues.apache.org/jira/browse/FLINK-22611?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Flink Jira Bot updated FLINK-22611:
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Labels: auto-deprioritized-major auto-deprioritized-minor (was:
auto-deprioritized-major stale-minor)
Priority: Not a Priority (was: Minor)
This issue was labeled "stale-minor" 7 days ago and has not received any
updates so it is being deprioritized. If this ticket is actually Minor, please
raise the priority and ask a committer to assign you the issue or revive the
public discussion.
> add documentation about the semantics of timestamp for time window output
> -------------------------------------------------------------------------
>
> Key: FLINK-22611
> URL: https://issues.apache.org/jira/browse/FLINK-22611
> Project: Flink
> Issue Type: Improvement
> Reporter: Zhenhao Li
> Priority: Not a Priority
> Labels: auto-deprioritized-major, auto-deprioritized-minor
>
> It seems that all windowed aggregation output receives the timestamp metadata
> if event time is being used for the processing.
> However, I couldn't find anything on the documentation pages about what
> timestamp value each output gets. Intuitively, it makes sense to assume it is
> the maximal timestamp from the input records of the window.
> After digging in the source code, I got the impression that the timestamp of
> the output is actually 1 millisecond before the window end time.
> See
> https://github.com/apache/flink/blob/99c2a415e9eeefafacf70762b6f54070f7911ceb/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/windowing/EvictingWindowOperator.java#L375
> and
> https://github.com/apache/flink/blob/99c2a415e9eeefafacf70762b6f54070f7911ceb/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/windows/TimeWindow.java#L84
> Correct me if I'm wrong. If I'm right, I think we should add documentation
> about it since this is very important because it is not uncommon to chain
> multiple windowed processes. Understanding the timestamp semantics is
> critical to the correctness of the code.
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