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Posted to issues@spark.apache.org by "Jacek Laskowski (JIRA)" <ji...@apache.org> on 2017/05/16 07:43:04 UTC
[jira] [Updated] (SPARK-4570) Add broadcast join to left semi join
[ https://issues.apache.org/jira/browse/SPARK-4570?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jacek Laskowski updated SPARK-4570:
-----------------------------------
Description:
For now, spark use broadcast join instead of hash join to optimize {{inner join}} when the size of one side data did not reach the {{AUTO_BROADCASTJOIN_THRESHOLD}}
However,Spark SQL will perform shuffle operations on each child relations while executing {{left semi join}} is more suitable for optimiztion with broadcast join.
We are planning to create a {{BroadcastLeftSemiJoinHash}} to implement the broadcast join for {{left semi join}}.
was:
For now, spark use broadcast join instead of hash join to optimize {{inner join}} when the size of one side data did not reach the {{AUTO_BROADCASTJOIN_THRESHOLD}}
However,Spark SQL will perform shuffle operations on each child relations while executing {{left semi join}} is more suitable for optimiztion with broadcast join.
We are planning to create a{{BroadcastLeftSemiJoinHash}} to implement the broadcast join for {{left semi join}}
> Add broadcast join to left semi join
> -------------------------------------
>
> Key: SPARK-4570
> URL: https://issues.apache.org/jira/browse/SPARK-4570
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 1.1.0
> Reporter: XiaoJing wang
> Assignee: XiaoJing wang
> Priority: Minor
> Fix For: 1.3.0
>
>
> For now, spark use broadcast join instead of hash join to optimize {{inner join}} when the size of one side data did not reach the {{AUTO_BROADCASTJOIN_THRESHOLD}}
> However,Spark SQL will perform shuffle operations on each child relations while executing {{left semi join}} is more suitable for optimiztion with broadcast join.
> We are planning to create a {{BroadcastLeftSemiJoinHash}} to implement the broadcast join for {{left semi join}}.
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