[jira] [Commented] (FLINK-18523) Advance watermark if there is no data in all of the partitions after some time

["Aljoscha Krettek (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-18523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17154474#comment-17154474 ] 

Aljoscha Krettek commented on FLINK-18523:
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You can define an idleness timeout on the DataStream API, see: https://ci.apache.org/projects/flink/flink-docs-master/dev/event_timestamps_watermarks.html#dealing-with-idle-sources.

For the Table API, maybe [~jark] or [~twalthr] could comment?

> 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, watermar 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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