[C++] Implement unique kernel for dictionary type #26386
Description
Calling the "unique" compute function on a ChunkedArray of dictionary type (as read by the CSV reader) errors with "Only hashing for data with equal dictionaries currently supported". But is it necessary to hash to get unique values from a dictionary type? The dictionary values are the unique values (for each chunk), they're already there.
Reporter: Neal Richardson / @nealrichardson
Assignee: Rok Mihevc / @rok
PRs and other links:
Note: This issue was originally created as ARROW-10403. Please see the migration documentation for further details.