[jira] [Commented] (FLINK-8594) Make producesUpdates in DataStreamGroupAggregate return false if it is a distinct group by without state retention configuration

["Timo Walther (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-8594?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16628930#comment-16628930 ] 

Timo Walther commented on FLINK-8594:
-------------------------------------

[~hequn8128] what is the status of this issue? I also wondered why a {{SELECT DISTINCT}} is not an append stream. 

> Make producesUpdates in DataStreamGroupAggregate return false if it is a distinct group by without state retention configuration 
> ---------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-8594
>                 URL: https://issues.apache.org/jira/browse/FLINK-8594
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>            Reporter: Hequn Cheng
>            Assignee: Hequn Cheng
>            Priority: Major
>
> Internally, the {{DISTINCT}} is translated into a {{GROUP BY}} with all distinct fields being keys and no aggregation functions. However, this kind of \{{GROUP BY}} don't generate update at all if the state retention time has not been configured. We can treat the result table as an append table. 
> Therefore, we can make the \{{producesUpdates}} function return false, so the downstream group by will not choose the correspond retract agg function, i.e., {{MaxWithRetractAggFunction}}



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