[ARROW-14284] [C++][Python] Improve error message when trying use SyncScanner when requiring async

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/29860
• Assignee: Weston Pace
• Reporter: Joris Van den Bossche
• Created: 11/Oct/21 15:18
• Updated: 11/Jan/23 08:38
• Resolved: 14/Oct/21 11:03

Description

See ARROW-14257

The current error message gives "Asynchronous scanning is not supported by SyncScanner"

Copying the comment of Weston Pace:

In Python it is always use_async=True. In R the scanner is hidden from the user on dataset writes but the option there is use_async as well. In C++ the option is UseAsync in the ScannerBuilder. How about,

"Writing datasets requires that the input scanner is configured to scan asynchronously via the use_async or UseAsync options."

Issue Links

• links to: GitHub Pull Request #11413