Group by on a combination of disitinct and non distinct aggregates can return
serialization errors with map side aggregations.
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Key: HIVE-222
URL: https://issues.apache.org/jira/browse/HIVE-222
Project: Hadoop Hive
Issue Type: Bug
Components: Query Processor
Reporter: Ashish Thusoo
Assignee: Ashish Thusoo
For queries of the form (groupby2_map.q in the source)
SELECT x, count(DISTINCT y), SUM(y) FROM t GROUP BY x
when map side aggregation is on
hive.map.aggr=true (This is off by default)
The following exception can occur:
[junit] Caused by: java.lang.ClassCastException: java.lang.Long cannot be
cast to java.lang.Double
[junit] at
org.apache.hadoop.hive.serde2.dynamic_type.DynamicSerDeTypeDouble.serialize(DynamicSerDeTypeDouble.java:60)
[junit] at
org.apache.hadoop.hive.serde2.dynamic_type.DynamicSerDeFieldList.serialize(DynamicSerDeFieldList.java:235)
[junit] at
org.apache.hadoop.hive.serde2.dynamic_type.DynamicSerDeStructBase.serialize(DynamicSerDeStructBase.java:81)
[junit] at
org.apache.hadoop.hive.serde2.dynamic_type.DynamicSerDe.serialize(DynamicSerDe.java:174)
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