[jira] [Created] (HIVE-20319) group by and union all always generate empty query result

["Wang Yan (JIRA)" <ji...@apache.org>]

Wang Yan created HIVE-20319:
-------------------------------

             Summary: group by and union all always generate empty query result
                 Key: HIVE-20319
                 URL: https://issues.apache.org/jira/browse/HIVE-20319
             Project: Hive
          Issue Type: Bug
          Components: Query Processor
    Affects Versions: 2.3.2
            Reporter: Wang Yan


The following query always generates empty results which is wrong.

{code:sql}
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;

{code}

Actual result : empty

Expected result: 

{code}

a

b

a

b

{code}

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

It seems like the fix in https://issues.apache.org/jira/browse/HIVE-12788 is insufficient.



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