[IMPALA-6468] Round() is inconsistent for Decimal and Double

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.11.0
• Fix Version/s: Impala 3.0
• Component/s: Backend
• Epic Color: ghx-label-3
• Assignee: Taras Bobrovytsky
• Reporter: Taras Bobrovytsky
• Created: 01/Feb/18 00:53
• Updated: 11/Jul/18 23:23
• Resolved: 26/Mar/18 20:38

Description

We round away from zero when rounding decimals:

select round(cast(-5.55 as decimal(10, 5)), 1);

-5.6

 

However, we round towards positive infinity for doubles.

select round(cast(-5.55 as double), 1);

-5.5

select round(cast(5.55 as double), 1);

5.6

 

This seems inconsistent.

Issue Links

• is duplicated by: IMPALA-7255 Incorrect result rounding midpoint negative numbers to negative precision