[jira] [Created] (SPARK-2176) extra unnecessary exchange operator in group by

[Reynold Xin (JIRA)]

Reynold Xin created SPARK-2176:
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             Summary: extra unnecessary exchange operator in group by
                 Key: SPARK-2176
                 URL: https://issues.apache.org/jira/browse/SPARK-2176
             Project: Spark
          Issue Type: Bug
          Components: SQL
            Reporter: Reynold Xin
            Assignee: Yin Huai


{code}
hql("explain select * from src group by key").collect().foreach(println)

[ExplainCommand [plan#27:0]]
[ Aggregate false, [key#25], [key#25,value#26]]
[  Exchange (HashPartitioning [key#25:0], 200)]
[   Exchange (HashPartitioning [key#25:0], 200)]
[    Aggregate true, [key#25], [key#25]]
[     HiveTableScan [key#25,value#26], (MetastoreRelation default, src, None), 
None]
{code}

There are two exchange operators.




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