[ARROW-9554] [Java] FixedWidthInPlaceVectorSorter sometimes produces wrong result

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: Java
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/25620
• Assignee: Unassigned
• Reporter: Steve M. Kim
• Created: 24/Jul/20 15:54
• Updated: 11/Jan/23 08:07
• Resolved: 24/Aug/20 02:30

Description

I noticed that FixedWidthInPlaceVectorSorter in the arrow-algorithms library produces the wrong result. A simple test case is a IntVector with the following values:

 

[0, 1, 2, 3, 4, 5, 30, 31, 32, 33, 34, 35, 60, 61, 62, 63, 64, 65, 6, 7, 8, 9, 10, 11, 36, 37, 38, 39, 40, 41, 66, 67, 68, 69, 70, 71]

 

The expected result of sorting is

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71]

What I actually observe is

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31, 32, 33, 34, 36, 35, 36, 60, 61, 62, 63, 64, 71, 71, 71, 71, 71, 65, 66, 67, 68, 69, 70, 71]

 

I have not yet determined whether any of the other sorters are also buggy.

Issue Links

• links to: GitHub Pull Request #7837