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https://issues.apache.org/jira/browse/FLINK-19896?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-19896:
-----------------------------------
    Labels: pull-request-available  (was: )

> Improve first-n-row fetching in the rank operator
> -------------------------------------------------
>
>                 Key: FLINK-19896
>                 URL: https://issues.apache.org/jira/browse/FLINK-19896
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Planner, Table SQL / Runtime
>            Reporter: Jun Zhang
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: flink-19896.patch
>
>
> Currently Deduplicate operator only supports first-row deduplication (ordered 
> by proc-time). In scenario of first-n-rows deduplication, the planner has to 
> resort to Rank operator.  However, Rank operator is less efficient than 
> Deduplicate due to larger state and more state access.
> This issue proposes to extend DeduplicateKeepFirstRowFunction to support 
> first-n-rows deduplication. And the original first-row deduplication would be 
> a special case of first-n-rows deduplication.



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