[ARROW-12031] [C++][CSV] infer CSV timestamps columns with fractional seconds

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 4.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/27860
• Assignee: Martin Nowak
• Reporter: Martin Nowak
• Created: 20/Mar/21 09:58
• Updated: 11/Jan/23 08:23
• Resolved: 22/Mar/21 17:12

Description

After implementing fractional second parsing in and ARROW-9107 and ARROW-10337, no support for inference of subsecond timestamps was added (see [code]([https://github.com/apache/arrow/blob/master/cpp/src/arrow/csv/inference_internal.h#L115), also mentioned in ARROW-3738).

The InferState logic could test for TimestampNS (with nanosecond resolution) after Timestamps with second resolution to not change existing inference results.

Wouldn't expect too much interest in trying to infer timestamps with milli- and microsecond resolution. The nanosecond resolution can already parse the lower resolution ones.

Issue Links

• links to: GitHub Pull Request #9761