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https://issues.apache.org/jira/browse/FLINK-18523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17157933#comment-17157933
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chen yong commented on FLINK-18523:
-----------------------------------
In DataStream API module , in version 1.11 by implementing WatermarkGenerator
interface can easily solve the problem, of course in the remaining version can
also be used by inheritance AssignerWithPeriodicWatermarks to realize many
logic to solve this problem, but it is not easy。
In the Table API/SQL Module, because the DataStream API and the Table API can
be converted to each other, according to the above mentioned can solve this
problem.But it can be difficult for users who are not very familiar with it.
> Advance watermark if there is no data in all of the partitions after some time
> ------------------------------------------------------------------------------
>
> Key: FLINK-18523
> URL: https://issues.apache.org/jira/browse/FLINK-18523
> Project: Flink
> Issue Type: New Feature
> Components: Table SQL / API
> Affects Versions: 1.11.0
> Reporter: chen yong
> Priority: Major
>
> In the case of window calculations and eventTime scenarios, watermark cannot
> update because the source does not have data for some reason, and the last
> Windows cannot trigger the calculations.
> One parameter, table.exec.source. Idle -timeout, can only solve the problem
> of ignoring parallelism of watermark alignment that does not occur.But when
> there is no watermark in each parallel degree, you still cannot update the
> watermark.
> Is it possible to add a lock-timeout parameter (which should be larger than
> maxOutOfOrderness with default of "-1 ms") and if the watermark is not
> updated beyond this time (i.e., there is no data), then the current time is
> taken and sent downstream as the watermark.
>
> thanks!
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