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Date: Mon, 8 Dec 2014 19:51:13 +0000 (UTC)
From: "Chao (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12760243.1418068229000.103452.1418068273636@Atlassian.JIRA>
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Subject: [jira] [Created] (HIVE-9041) Generate better plan for queries
 containing both union and multi-insert [Spark Branch]
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Chao created HIVE-9041:
--------------------------

             Summary: Generate better plan for queries containing both union and multi-insert [Spark Branch]
                 Key: HIVE-9041
                 URL: https://issues.apache.org/jira/browse/HIVE-9041
             Project: Hive
          Issue Type: Bug
          Components: Spark
    Affects Versions: spark-branch
            Reporter: Chao


This is a follow-up for HIVE-8920. For queries like:

{code}
from (select * from table0 union all select * from table1) s
insert overwrite table table3 select s.x, count(1) group by s.x
insert overwrite table table4 select s.y, count(1) group by s.y;
{code}

Currently we generate the following plan:

{noformat}
    M1    M2
      \  / \
       U3   R5
       |
       R4
{noformat}

It's better, however, to have the following plan:

{noformat}
   M1  M2
   |\  /|
   | \/ |
   | /\ |
   R1  R2
{noformat}

Also, we can do some reseach in this JIRA to see if it's possible
to remove UnionWork once and for all.


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