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Posted to issues@flink.apache.org by "Danny Chen (Jira)" <ji...@apache.org> on 2020/05/20 09:04:00 UTC

[jira] [Commented] (FLINK-16165) NestedLoopJoin fallback to HashJoin when build records number is very large

    [ https://issues.apache.org/jira/browse/FLINK-16165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17111960#comment-17111960 ] 

Danny Chen commented on FLINK-16165:
------------------------------------

Discussed offline with [~lzljs3620320], we have decided to move this feature to 1.12.0.

> NestedLoopJoin fallback to HashJoin when build records number is very large
> ---------------------------------------------------------------------------
>
>                 Key: FLINK-16165
>                 URL: https://issues.apache.org/jira/browse/FLINK-16165
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Planner
>            Reporter: Jingsong Lee
>            Assignee: Jingsong Lee
>            Priority: Critical
>             Fix For: 1.12.0
>
>
> Now, if the statistic is not so accurate, maybe choose wrong join type to nested loop join.
> If build records number is very large, this lead to very slow join, the user looks like the join is in Hang.
> It is a stability problem, We should fallback to hash join in runtime to avoid this hang.



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