[IMPALA-4849] Case expression with constant condition generates IllegalStateException

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Impala 2.9.0
• Fix Version/s: Impala 2.9.0
• Component/s: Frontend
• Assignee: Thomas Tauber-Marshall
• Reporter: Joe McDonnell
• Created: 31/Jan/17 22:28
• Updated: 09/Feb/17 21:08
• Resolved: 09/Feb/17 21:08

Description

The following SQLs generate an IllegalStateException:

select distinct case when true then id else 0 end from functional.alltypes;
select case when true then id else 0 end from functional.alltypes group by id;

These SQLs do not produce an error:

select distinct case when true then 0 else id end from functional.alltypes;
select distinct case when id=id then id else 0 end from functional.alltypes;
select case when true then id else 0 end from functional.alltypes;

This seems to be related to the optimization for case expressions with a constant condition interacting with distinct.