jorisvandenbossche commented on a change in pull request #12153:
URL: https://github.com/apache/arrow/pull/12153#discussion_r785757447
##########
File path: python/pyarrow/orc.py
##########
@@ -175,3 +176,33 @@ def write_table(table, where):
writer = ORCWriter(where)
writer.write(table)
writer.close()
+
+
+def read_table(source, columns=None, filesystem=None):
+ """
+ Read a table from ORC format
Review comment:
```suggestion
Read a Table from an ORC file.
```
##########
File path: python/pyarrow/orc.py
##########
@@ -175,3 +176,33 @@ def write_table(table, where):
writer = ORCWriter(where)
writer.write(table)
writer.close()
+
+
+def read_table(source, columns=None, filesystem=None):
+ """
+ Read a table from ORC format
+
+ Parameters
+ ----------
+ source : str, pyarrow.NativeFile, or file-like object
+ If a string passed, can be a single file name or directory name. For
+ file-like objects, only read a single file. Use pyarrow.BufferReader to
+ read a file contained in a bytes or buffer-like object.
+ 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'. If empty, no columns will be read. Note
+ that the table will still have the correct num_rows set despite having
+ no columns.
Review comment:
This last sentence doesn't actually seem to be true:
```
In [1]: import pyarrow as pa
In [2]: from pyarrow import orc
In [3]: orc.write_table(pa.table({'a': [1, 2, 3]}), "test.orc")
In [4]: result = orc.ORCFile("test.orc").read(columns=[])
In [5]: result.num_rows
Out[5]: 0
In [6]: result.num_columns
Out[6]: 0
```
##########
File path: python/pyarrow/tests/test_orc.py
##########
@@ -169,6 +171,36 @@ def test_orcfile_empty(datadir):
assert table.schema == expected_schema
+def test_readwrite(tmpdir):
+ from pyarrow import orc
+ a = pa.array([1, None, 3, None])
+ b = pa.array([None, "Arrow", None, "ORC"])
+ table = pa.table({"int64": a, "utf8": b})
+ file = tmpdir.join("test.orc")
+ orc.write_table(table, file)
+ output_table = orc.read_table(file)
+ assert table.equals(output_table)
+
Review comment:
Can you add one more read_table call here with eg `columns=["int64"]`,
just to make sure that this keyword is properly passed through
##########
File path: python/pyarrow/orc.py
##########
@@ -175,3 +176,33 @@ def write_table(table, where):
writer = ORCWriter(where)
writer.write(table)
writer.close()
+
+
+def read_table(source, columns=None, filesystem=None):
+ """
+ Read a table from ORC format
+
+ Parameters
+ ----------
+ source : str, pyarrow.NativeFile, or file-like object
+ If a string passed, can be a single file name or directory name. For
+ file-like objects, only read a single file. Use pyarrow.BufferReader to
+ read a file contained in a bytes or buffer-like object.
+ 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'. If empty, no columns will be read. Note
+ that the table will still have the correct num_rows set despite having
+ no columns.
+ filesystem : FileSystem, default None
+ If nothing passed, paths assumed to be found in the local on-disk
+ filesystem.
Review comment:
I know this is copied from the parquet read_table docstring, but I am
not sure this is fully correct? I suppose passing a URI for eg a remote file
also works?
##########
File path: python/pyarrow/orc.py
##########
@@ -175,3 +176,33 @@ def write_table(table, where):
writer = ORCWriter(where)
writer.write(table)
writer.close()
+
+
+def read_table(source, columns=None, filesystem=None):
+ """
+ Read a table from ORC format
+
+ Parameters
+ ----------
+ source : str, pyarrow.NativeFile, or file-like object
+ If a string passed, can be a single file name or directory name. For
Review comment:
For ORC, this implementation of `read_table` does not support reading
directories. So the above should only be a single file name.
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