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

["Jonas Jarutis (JIRA)" <ji...@apache.org>]

Jonas Jarutis created SPARK-16991:
-------------------------------------

             Summary: 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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