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Posted to issues@spark.apache.org by "Apache Spark (Jira)" <ji...@apache.org> on 2020/09/09 10:07:00 UTC

[jira] [Assigned] (SPARK-32830) Optimize Skewed BroadcastNestedLoopJoin with AE

     [ https://issues.apache.org/jira/browse/SPARK-32830?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-32830:
------------------------------------

    Assignee:     (was: Apache Spark)

> Optimize Skewed BroadcastNestedLoopJoin with AE
> -----------------------------------------------
>
>                 Key: SPARK-32830
>                 URL: https://issues.apache.org/jira/browse/SPARK-32830
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>    Affects Versions: 3.1.0
>            Reporter: angerszhu
>            Priority: Major
>
> For BroadcastNestedLoopJoin, we will broadcast boradcast-side child to all executor and use stream side partition's data traversal broadcast-side data one-by-one. 
> We have meet some case that stream side data skew and all success task wait for skewed partition to finish.
> We know that the execution time increases exponentially with the amount of partition's data.
> If skewd with 100x,  skewed partition's data will execute 100x than non-skewed part.
> It is a bottleneck, with AE, we can avoid this by  split skewed part's data  to make it more balanced.
>  



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