coady opened a new issue, #36149:
URL: https://github.com/apache/arrow/issues/36149
### Describe the bug, including details regarding any error messages,
version, and platform.
Grouping on empty keys aggregates against the whole table (relates to
#14896). But there are 3 hash aggregate functions which do not have
corresponding scalar aggregate functions: `hash_distinct`, `hash_list`, and
`hash_one`. Grouping on empty keys with those raises a key error.
```python
In []: table = pa.table({'key': list('aba'), 'value': [0, 1, 2]})
In []: table.group_by(['key']).aggregate([('value', 'list')])
Out[]:
pyarrow.Table
key: string
value_list: list<item: int64>
child 0, item: int64
----
key: [["a","b"]]
value_list: [[[0,2],[1]]]
In []: table.group_by([]).aggregate([('value', 'list')])
...
ArrowKeyError: No function registered with name: list
In []: table.group_by([]).aggregate([('value', 'min')])
Out[]:
pyarrow.Table
value_min: int64
----
value_min: [[0]]
```
### Component(s)
C++, Python
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