Steve Carlin created HIVE-22260:
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             Summary: Materialized view rewriting does not support `UNION` 
operator, exact match can work under view
                 Key: HIVE-22260
                 URL: https://issues.apache.org/jira/browse/HIVE-22260
             Project: Hive
          Issue Type: Sub-task
          Components: CBO
    Affects Versions: 3.1.2
            Reporter: Steve Carlin
         Attachments: complex0.sql

In this case, a view can be created that hides some nastier syntax like a 
"union".  

A materialized view can contain the view with a simple query.  So if the end 
query just uses the view, it should rewrite to the materialized view.  A script 
is attached.

An example of this:

create view logical_complex0 as

with t as

(select c1 as a, c2 as b from tab1 where c2 in (select f from logical_simple 
where g > 0)

union

select tab3.c1 as c, tab4.c2 as d from tab3, tab4 where tab3.c2 = tab4.c2)

select a, b

from t;

 

-- query separator

 

create materialized view aview_complex0 stored as orc as

select a as x, b as y, count(*)

from logical_complex0

group by 1, 2;



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