[HIVE-22260] Materialized view rewriting does not support `UNION` operator, exact match can work under view

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.1.2
• Component/s: CBO, Materialized views
• Assignee: Unassigned
• Reporter: Steve Carlin
• Created: 27/Sep/19 21:03
• Updated: 27/Sep/19 23:20

Description

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. 

Furthermore, an exception is thrown when it contains the "union" while creating the view.  At a minimum, we should print a friendlier message when the rewrite fails.

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;