[jira] [Commented] (SPARK-4483) Optimization about reduce memory costs during the HashOuterJoin

["Apache Spark (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-4483?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14218871#comment-14218871 ] 

Apache Spark commented on SPARK-4483:
-------------------------------------

User 'tianyi' has created a pull request for this issue:
https://github.com/apache/spark/pull/3375

> Optimization about reduce memory costs during the HashOuterJoin
> ---------------------------------------------------------------
>
>                 Key: SPARK-4483
>                 URL: https://issues.apache.org/jira/browse/SPARK-4483
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 1.1.0
>            Reporter: Yi Tian
>            Priority: Minor
>
> In {{HashOuterJoin.scala}}, spark read data from both side of join operation before zip them together. It is a waste for memory. We are trying to read data from only one side, put them into hashmap, and then generate the {{JoinedRow}} with data from other side one by one.
> Currently, we could only do this optimization for {{left outer join}} and {{right outer join}}. For {{full outer join}},  we will do somthing in another issue.



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