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Posted to issues@spark.apache.org by "Dongjoon Hyun (Jira)" <ji...@apache.org> on 2022/01/27 19:58:00 UTC

[jira] [Commented] (SPARK-37193) DynamicJoinSelection.shouldDemoteBroadcastHashJoin should not apply to outer joins

    [ https://issues.apache.org/jira/browse/SPARK-37193?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17483408#comment-17483408 ] 

Dongjoon Hyun commented on SPARK-37193:
---------------------------------------

I removed the `Fix Version` because this is reverted.

> DynamicJoinSelection.shouldDemoteBroadcastHashJoin should not apply to outer joins
> ----------------------------------------------------------------------------------
>
>                 Key: SPARK-37193
>                 URL: https://issues.apache.org/jira/browse/SPARK-37193
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.1.1
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>            Priority: Major
>
> {{DynamicJoinSelection.shouldDemoteBroadcastHashJoin}} will prevent AQE from converting Sort merge join into a broadcast join because SMJ is faster when the side that would be broadcast has a lot of empty partitions.
>  This makes sense for inner joins which can short circuit if one side is empty.
>  For (left,right) outer join, the streaming side still has to be processed so demoting broadcast join doesn't have the same advantage.



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