[ARROW-11748] [C++] Ensure Decimal128 and Decimal256's fields are in native endian order

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 6.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/27604
• Assignee: yibocai#1
• Reporter: Ben Kietzman
• Created: 23/Feb/21 19:59
• Updated: 11/Jan/23 08:21
• Resolved: 22/Jul/21 14:23

Description

Currently Decimal128 and Decimal256's fields are exclusively in littleendian order, which can yield surprising results when reinterpret_cast}}ing entries of a buffer to {{Decimal128* on a bigendian platform, see https://github.com/apache/arrow/pull/9554

These utility classes will be more useful if they are always usable from a buffer without swizzling.

Issue Links

• links to: GitHub Pull Request #10651