[Python] Error reading IPC file with no record batches

[asfimport]

When using the RecordBatchFileWriter without actually writing a record batch. The magic byte at the beginning of the file is not written. This causes the exception File is smaller than indicated metadata size when reading that file with the RecordBatchFileReader.

Reporter: Rik Coenders
Assignee: Wes McKinney / @wesm

PRs and other links:

• GitHub Pull Request #3095

_{Note: This issue was originally created as ARROW-3894. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Is this in Python?

[asfimport]

Wes McKinney / @wesm:
Making the assumption that this is C++/Python related, but someone can update if they find out this is not the case

[asfimport]

Rik Coenders:
I have got the issue in python, but looking at the code my assumption is that this problem is in the underlying c++ library, so it might occur in other languages as well.

[asfimport]

Rik Coenders:
To reproduce:

import pyarrow
import tempfile

schema = pyarrow.schema([('field', pyarrow.int64())])
filename = tempfile.mkstemp()[1]

with pyarrow.OSFile(filename, 'w') as file:
    writer = pyarrow.RecordBatchFileWriter(file, schema)
    writer.close()

with pyarrow.OSFile(filename, 'r') as file:
    reader = pyarrow.RecordBatchFileReader(file)
    reader.read_all()

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 3095
#3095