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https://issues.apache.org/jira/browse/FLINK-6969?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16062987#comment-16062987
 ] 

ASF GitHub Bot commented on FLINK-6969:
---------------------------------------

Github user wuchong commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4183#discussion_r123989165
  
    --- Diff: 
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/queryConfig.scala
 ---
    @@ -92,6 +100,23 @@ class StreamQueryConfig private[table] extends 
QueryConfig {
         this
       }
     
    +  /**
    +    * Specifies a deferred computation time for deferred computation.
    +    */
    +  def withDeferredComputationTime(deferredComputationTime: Time): 
StreamQueryConfig = {
    +
    +    if (deferredComputationTime.toMilliseconds < 1) {
    --- End diff --
    
    I think it can be zero or one. 


> 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
>
> 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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