[jira] [Created] (SPARK-17653) Optimizer should remove unnecessary distincts (in multiple unions)

["Reynold Xin (JIRA)" <ji...@apache.org>]

Reynold Xin created SPARK-17653:
-----------------------------------

             Summary: Optimizer should remove unnecessary distincts (in multiple unions)
                 Key: SPARK-17653
                 URL: https://issues.apache.org/jira/browse/SPARK-17653
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 2.0.0
            Reporter: Reynold Xin


Query:

{code}
select 1 a union select 2 b union select 3 c
{code}


Explain plan:
{code}
== Physical Plan ==
*HashAggregate(keys=[a#13], functions=[])
+- Exchange hashpartitioning(a#13, 200)
   +- *HashAggregate(keys=[a#13], functions=[])
      +- Union
         :- *HashAggregate(keys=[a#13], functions=[])
         :  +- Exchange hashpartitioning(a#13, 200)
         :     +- *HashAggregate(keys=[a#13], functions=[])
         :        +- Union
         :           :- *Project [1 AS a#13]
         :           :  +- Scan OneRowRelation[]
         :           +- *Project [2 AS b#14]
         :              +- Scan OneRowRelation[]
         +- *Project [3 AS c#15]
            +- Scan OneRowRelation[]
{code}

Only one distinct should be necessary.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org