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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-6969) Add support for deferred computation for group window aggregates
Date Thu, 06 Jul 2017 14:47:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6969?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16076623#comment-16076623

ASF GitHub Bot commented on FLINK-6969:

Github user sunjincheng121 commented on the issue:

    @fhueske  @wuchong I have updated the PR. I appreciated  if you can have look at it.

> Add support for deferred computation for group window aggregates
> ----------------------------------------------------------------
>                 Key: FLINK-6969
>                 URL: https://issues.apache.org/jira/browse/FLINK-6969
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: Fabian Hueske
>            Assignee: sunjincheng
>         Attachments: screenshot-1.png
> Deferred computation is a strategy to deal with late arriving data and avoid updates
of previous results. Instead of computing a result as soon as it is possible (i.e., when a
corresponding watermark was received), deferred computation adds a configurable amount of
slack time in which late data is accepted before the result is compute. For example, instead
of computing a tumbling window of 1 hour at each full hour, we can add a deferred computation
interval of 15 minute to compute the result quarter past each full hour.
> This approach adds latency but can reduce the number of update esp. in use cases where
the user cannot influence the generation of watermarks. It is also useful if the data is emitted
to a system that cannot update result (files or Kafka). The deferred computation interval
should be configured via the {{QueryConfig}}.

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