[HIVE-25754] Fix column projection for union all queries with multiple aliases

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Assignee: Marton Bod
• Reporter: Marton Bod
• Created: 01/Dec/21 10:49
• Updated: 23/May/23 12:15
• Resolved: 02/Dec/21 08:53

Description

Given two tables:

create table source1 (dt string, d1 int, d2 int) stored as orc;
create table source2 (dt string, d1 int, d2 int) stored as orc;
insert into source1 values ('20211107', 1, 2);
insert into source2 values ('20211108', 11, 22);

If you run this query with UNION ALL, the key column will be missing from the output:

select explode(map('D219', D219
,'D220', D220)) as (key, value) from (
   {{select '20211107' as date_key
,1 as D219
,2 as D220
) t}}
union all
select explode(map('D221', D221
,'D222', D222)) as (key, value)
from (}}
  {{select '20211107' as date_key
,1 as D221
,2 as D222
) t

Result:

1
2
11
22

 Correct result should be:

D219 1
D220 2
D221 11
D222 22

Issue Links

• duplicates: HIVE-22601 Some columns will be lost when a UDTF has multiple aliases in some cases