ketozhang commented on issue #43626:
URL: https://github.com/apache/arrow/issues/43626#issuecomment-2968225055
I tripped up in this thinking that `nullable=True` is the same as optional
columns.
```python
>>> import pyarrow as pa
>>>
>>> schema = pa.schema(
... [
... pa.field("id", pa.int64()),
... pa.field("nullable", pa.string(), nullable=True),
... ]
... )
>>>
>>> table = pa.Table.from_arrays(
... [pa.array([1, 2, 3], type=pa.int64())], names=["id"]
... )
>>>
>>> table.cast(schema)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pyarrow/table.pxi", line 4717, in pyarrow.lib.Table.cast
ValueError: Target schema's field names are not matching the table's field
names: ['id'], ['id', 'nullable']
```
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