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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] [Commented] (SPARK-32830) Optimize Skewed
BroadcastNestedLoopJoin with AE
[ https://issues.apache.org/jira/browse/SPARK-32830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17192758#comment-17192758 ]
Apache Spark commented on SPARK-32830:
--------------------------------------
User 'AngersZhuuuu' has created a pull request for this issue:
https://github.com/apache/spark/pull/29692
> 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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