[ARROW-14129] [C++] An empty dictionary array crashes on `unique` and `value_counts`.

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 5.0.0
• Fix Version/s: 6.0.0
• Component/s: C++, Python
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/29719
• Assignee: David Li
• Reporter: A. Coady
• Created: 24/Sep/21 21:33
• Updated: 11/Jan/23 08:37
• Resolved: 27/Sep/21 19:16

Description

import pyarrow as pa
arr = pa.array(range(3)).dictionary_encode()
assert not arr[:0]
arr[:0].unique() # Check failed: (data->dictionary) != (nullptr) 

Issue Links

• links to: GitHub Pull Request #11249