[ARROW-9299] [Python] Expose ORC metadata() in Python ORCFile

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.17.1
• Fix Version/s: 5.0.0
• Component/s: C++, Python
• Labels: orc pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/17254
• Assignee: Ian Alexander Joiner
• Reporter: Jeremy Dyer
• Created: 02/Jul/20 15:24
• Updated: 11/Jan/23 08:05
• Resolved: 27/May/21 15:53

Description

There is currently no way for a user to directly access the underlying ORC metadata of a given file. It seems the C++ functions and objects already existing and rather the plumbing is just missing the the cython/python and potentially a few c++ shims. Giving users the ability to retrieve the metadata without first reading the entire file could help numerous applications to increase their query performance by allowing them to intelligently determine which ORC stripes should be read.  

This would allow for something like 

import pyarrow as pa 
orc_metadata = pa.orc.ORCFile(filename).metadata()

Issue Links

• links to: GitHub Pull Request #10157