[HIVE-14251] Union All of different types resolves to incorrect data

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.2.0
• Component/s: Query Planning
• Target Version/s: 1.3.0, 2.0.2

Release Note

With this change, Hive will only perform implicit conversion within each type groups including string group, number group or date group, not across groups. So in order to union a string type with a date type, a explicit cast from string to date or from date to string is needed.

• Assignee: Aihua Xu
• Reporter: Aihua Xu
• Created: 15/Jul/16 18:25
• Updated: 26/Jul/17 03:30
• Resolved: 14/Sep/16 18:52

Description

create table src(c1 date, c2 int, c3 double);
insert into src values ('2016-01-01',5,1.25);
select * from
(select c1 from src union all
select c2 from src union all
select c3 from src) t;

It will return NULL for the c1 values. Seems the common data type is resolved to the last c3 which is double.

Issue Links

• links to: Code review