[ARROW-14378] [R] Make custom extension classes for (some) cols with row-level metadata

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: R
• External issue URL: https://github.com/apache/arrow/issues/29946
• Assignee: Unassigned
• Reporter: Jonathan Keane
• Created: 19/Oct/21 13:22
• Updated: 11/Jan/23 08:39
• Resolved: 13/Jul/22 15:54

Description

The major usecase for this is SF columns which have attributes/metadata for each element of a column. We originally stored these in our standard column-level metadata, but that was very fragile and took forever, so we disabled it ARROW-13189

This will likely take some steps to accomplish. I've sketched out some in the subtasks here (though if we have a different approach, we could do that directly)