[jira] [Created] (SPARK-2148) Document custom class as key needing equals() AND hashcode()

["Andrew Ash (JIRA)" <ji...@apache.org>]

Andrew Ash created SPARK-2148:
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             Summary: Document custom class as key needing equals() AND hashcode()
                 Key: SPARK-2148
                 URL: https://issues.apache.org/jira/browse/SPARK-2148
             Project: Spark
          Issue Type: Bug
          Components: Documentation
    Affects Versions: 1.0.0
            Reporter: Andrew Ash


Several support requests on user@ have been tracked down to using a custom class as the key in a {{groupByKey()}} or {{reduceByKey()}} that has a custom {{equals()}} method but not the corresponding custom {{hashcode()}} method.

Let's add a note in the documentation that custom keys need both {{equals()}} and {{hashcode()}} overridden, never just {{equals()}}

The right place for this addition might be as a sub-section or note in http://spark.apache.org/docs/latest/programming-guide.html#working-with-key-value-pairs



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