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From "Cheng Lian (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SPARK-6319) DISTINCT doesn't work for binary type
Date Fri, 13 Mar 2015 12:10:38 GMT
Cheng Lian created SPARK-6319:
---------------------------------

             Summary: DISTINCT doesn't work for binary type
                 Key: SPARK-6319
                 URL: https://issues.apache.org/jira/browse/SPARK-6319
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 1.2.1, 1.1.1, 1.0.2, 1.3.0
            Reporter: Cheng Lian


Spark shell session for reproduction:
{noformat}
scala> import sqlContext.implicits._
scala> import org.apache.spark.sql.types._
scala> Seq(1, 1, 2, 2).map(i => Tuple1(i.toString)).toDF("c").select($"c" cast BinaryType).distinct.show()
...
CAST(c, BinaryType)
[B@43f13160
[B@5018b648
[B@3be22500
[B@476fc8a1
{noformat}
Spark SQL uses plain byte arrays to represent binary values. However, arrays are compared
by reference rather than by value. On the other hand, the DISTINCT operator uses a {{HashSet}}
and its {{.contains}} method to check for duplicated values. These two facts together cause
the problem.



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