[jira] [Created] (HIVE-9041) Generate better plan for queries containing both union and multi-insert [Spark Branch]

[Chao (JIRA)]

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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