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https://issues.apache.org/jira/browse/FLINK-8144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16268465#comment-16268465
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ASF GitHub Bot commented on FLINK-8144:
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Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/5063
Thank you @dianfu for the discussion.
I raised concerns about this PR because it seem to me to optimize for a
special use case and possibly cause regression for more common workloads.
However, I don't have numbers to back my assumptions.
If this is a big issue for you, we can also benchmark the impact of the
change for periodic and punctuated watermarks to check how it affects the
performance.
> Optimize the timer logic in RowTimeUnboundedOver
> ------------------------------------------------
>
> Key: FLINK-8144
> URL: https://issues.apache.org/jira/browse/FLINK-8144
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Reporter: Dian Fu
> Assignee: Dian Fu
> Fix For: 1.5.0
>
>
> Currently the logic of {{RowTimeUnboundedOver}} is as follows:
> 1) When element comes, buffer it in MapState and and register a timer at
> {{current watermark + 1}}
> 2) When event timer triggered, scan the MapState and find the elements below
> the current watermark and process it. If there are remaining elements to
> process, register a new timer at {{current watermark + 1}}.
> Let's assume that watermark comes about 5 seconds later than the event on
> average, then we will scan about 5000 times the MapState before actually
> processing the events.
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