A. Coady created ARROW-15735:
--------------------------------
Summary: [C++] Hash aggregate functions to return first and last
value from a group.
Key: ARROW-15735
URL: https://issues.apache.org/jira/browse/ARROW-15735
Project: Apache Arrow
Issue Type: New Feature
Components: C++
Reporter: A. Coady
Follow-up to ARROW-13993, which implemented `hash_one` to select an arbitrary
value, as the core engine lack support for ordering. I think `first` and `last`
will still be in demand though, based on pandas and sql usage.
It could be done without core changes by using `min_max` on an array of
indices. For that reason, maybe it would be better as
`hash_\{first,last}_index`, suitable for use with `take`.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
