Weston Pace created ARROW-13436:
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Summary: [Python][Doc] Clarify what should be expected if
read_table is passed an empty list of columns
Key: ARROW-13436
URL: https://issues.apache.org/jira/browse/ARROW-13436
Project: Apache Arrow
Issue Type: Bug
Components: Python
Reporter: Weston Pace
The documentation for pyarrow.parquet.read_table states:
* *columns* (_list_) – If not None, only these columns will be read from the
file. A column name may be a prefix of a nested field, e.g. ‘a’ will select
‘a.b’, ‘a.c’, and ‘a.d.e’.
It is not clear what should be the expected result if columns is an empty list.
In pyarrow 3.0 this read in all columns (as long as use_legacy_dataset=False).
In pyarrow 4.0 this doesn't read in any columns. I think this behavior (not
reading in any columns) is the correct behavior (since None can be used for all
columns) but we should clarify that in the docs.
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