[HIVE-20319] group by and union all always generate empty query result

• Type: Bug
• Status: Open
• Priority: Blocker
• Resolution: Unresolved
• Affects Version/s: 2.3.2
• Component/s: Query Processor

Environment

Run on MR, hadoop 2.7.3

• Assignee: Unassigned
• Reporter: Wang Yan
• Due: 06/Aug/18
• Created: 06/Aug/18 15:56
• Updated: 27/Sep/18 17:57

Description

The following query always generates empty results which is wrong.

create table if not exists test_table(column1 string, column2 int);
insert into test_table values('a',1),('b',2);
set hive.optimize.union.remove=true;

select column1 from test_table group by column1
union all
select column1 from test_table group by column1;

Actual result : empty

Expected result: 

a

b

a

b

Note that correct result is generated when set hive.optimize.union.remove=false.

It seems like the fix in HIVE-12788 is insufficient.

Issue Links

• duplicates: HIVE-12812 Enable mapred.input.dir.recursive by default to support union with aggregate function