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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