[jira] [Commented] (SPARK-16991) Full outer join followed by inner join produces wrong results

["Dongjoon Hyun (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-16991?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15414922#comment-15414922 ] 

Dongjoon Hyun commented on SPARK-16991:
---------------------------------------

Hi, [~jjarutis].
Thank you for reproducible issue reporting. The root cause seems that `EliminateOuterJoin` optimizer remove the case wrongly.
I'll make a PR soon.

> Full outer join followed by inner join produces wrong results
> -------------------------------------------------------------
>
>                 Key: SPARK-16991
>                 URL: https://issues.apache.org/jira/browse/SPARK-16991
>             Project: Spark
>          Issue Type: Bug
>    Affects Versions: 2.0.0
>            Reporter: Jonas Jarutis
>            Priority: Critical
>
> I found strange behaviour using fullouter join in combination with inner join. It seems that inner join can't match values correctly after full outer join. Here is a reproducible example in spark 2.0.
> {code}
>       ____              __
>      / __/__  ___ _____/ /__
>     _\ \/ _ \/ _ `/ __/  '_/
>    /___/ .__/\_,_/_/ /_/\_\   version 2.0.0
>       /_/
>          
> Using Scala version 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_45)
> Type in expressions to have them evaluated.
> Type :help for more information.
> scala> val a = Seq((1,2),(2,3)).toDF("a","b")
> a: org.apache.spark.sql.DataFrame = [a: int, b: int]
> scala> val b = Seq((2,5),(3,4)).toDF("a","c")
> b: org.apache.spark.sql.DataFrame = [a: int, c: int]
> scala> val c = Seq((3,1)).toDF("a","d")
> c: org.apache.spark.sql.DataFrame = [a: int, d: int]
> scala> val ab = a.join(b, Seq("a"), "fullouter")
> ab: org.apache.spark.sql.DataFrame = [a: int, b: int ... 1 more field]
> scala> ab.show
> +---+----+----+
> |  a|   b|   c|
> +---+----+----+
> |  1|   2|null|
> |  3|null|   4|
> |  2|   3|   5|
> +---+----+----+
> scala> ab.join(c, "a").show
> +---+---+---+---+
> |  a|  b|  c|  d|
> +---+---+---+---+
> +---+---+---+---+
> {code}
> Meanwhile, without the full outer, inner join works fine.
> {code}
> scala> b.join(c, "a").show
> +---+---+---+
> |  a|  c|  d|
> +---+---+---+
> |  3|  4|  1|
> +---+---+---+
> {code}



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