[ARROW-15152] [C++] Implement a `hash_list` aggregate function

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 6.0.1
• Fix Version/s: 8.0.0
• Component/s: C++, Python
• Labels: good-second-issue kernel pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/30658
• Assignee: Dhruv Vats
• Reporter: A. Coady
• Created: 19/Dec/21 23:21
• Updated: 11/Jan/23 08:44
• Resolved: 15/Mar/22 14:43

Description

For more advanced aggregations, it's helpful to be able to gather the grouped values into a list array. Pandas and Polars both have that feature. And `hash_distinct` already aggregates to lists, so all the building blocks are there.

Issue Links

• links to: GitHub Pull Request #12484