[IMPALA-6183] Converting Decimal to Double loses precision

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.7.0, Impala 2.8.0, Impala 2.9.0, Impala 2.10.0, Impala 2.11.0
• Fix Version/s: Impala 2.11.0
• Component/s: Backend
• Epic Color: ghx-label-1
• Assignee: Taras Bobrovytsky
• Reporter: Taras Bobrovytsky
• Created: 13/Nov/17 23:47
• Updated: 30/Aug/18 18:34
• Resolved: 15/Nov/17 03:55

Description

The following query returns a correct result:

select cast(1.1112223334445559 as double)

Result:

1.111222333444556

However, if we first convert the literal to a decimal, we lose precision.

select cast(cast(1.1112223334445559 as decimal(38, 37)) as double)

Result:

1.111222340799091

Issue Links

• relates to: IMPALA-5956 Add TPC-DS q31 and q89 to test suite