[jira] [Commented] (SPARK-12613) Elimination of Outer Join by Parent Join Condition

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

    [ https://issues.apache.org/jira/browse/SPARK-12613?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15080665#comment-15080665 ] 

Apache Spark commented on SPARK-12613:
--------------------------------------

User 'gatorsmile' has created a pull request for this issue:
https://github.com/apache/spark/pull/10566

> Elimination of Outer Join by Parent Join Condition
> --------------------------------------------------
>
>                 Key: SPARK-12613
>                 URL: https://issues.apache.org/jira/browse/SPARK-12613
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 1.6.0
>            Reporter: Xiao Li
>            Priority: Critical
>
> Given an outer join is involved in another join (called parent join), when the join type of the parent join is inner, left-semi, left-outer and right-outer, checking if the join condition of the parent join satisfies the following two conditions:
>  1) there exist null filtering predicates against the columns in the null-supplying side of parent join.
>  2) these columns are from the child join.
>  If having such join predicates, execute the elimination rules:
>  - full outer -> inner if both sides of the child join have such predicates
>  - left outer -> inner if the right side of the child join has such predicates
>  - right outer -> inner if the left side of the child join has such predicates
>  - full outer -> left outer if only the left side of the child join has such predicates
>  - full outer -> right outer if only the right side of the child join has such predicates



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