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Posted to issues@spark.apache.org by "Herman van Hovell (JIRA)" <ji...@apache.org> on 2015/08/07 15:59:45 UTC

[jira] [Created] (SPARK-9740) first/last aggregate NULL behavior

Herman van Hovell created SPARK-9740:
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             Summary: first/last aggregate NULL behavior
                 Key: SPARK-9740
                 URL: https://issues.apache.org/jira/browse/SPARK-9740
             Project: Spark
          Issue Type: Sub-task
          Components: SQL
    Affects Versions: 1.6.0
            Reporter: Herman van Hovell
            Priority: Minor


The FIRST/LAST aggregates implemented as part of the new UDAF interface, return the first or last non-null value (if any) found. This is a departure from the behavior of the old FIRST/LAST aggregates and from the FIRST_VALUE/LAST_VALUE aggregates in Hive. These would return a null value, if that happened to be the first/last value seen. SPARK-9592 tries to 'fix' this behavior for the old UDAF interface.

Hive makes this behavior configurable, by adding a skipNulls flag. I would suggest to do the same, and make the default behavior compatible with Hive.



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