[ARROW-5432] [Python] Add 'read_at' method to pyarrow.NativeFile

• Type: New Feature
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.13.0
• Fix Version/s: 0.14.0
• Component/s: Python
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/21885
• Assignee: Antoine Pitrou
• Reporter: Ivan Dimitrov
• Created: 28/May/19 22:10
• Updated: 11/Jan/23 07:40
• Resolved: 30/May/19 15:34

Description

We'd like to open a file (using HadoopFileSystem) and then read a block of data specified by the offset and the length. We don't want any read ahead to happen. 

The libhdfs driver supprots hdfsPread, and it exposes a ReadAt method in the RandomAccessFile interface. However, there is no way to access it from python. 

We add a read_at method to pyarrow.NativeFile that would expose this functionality. 

Issue Links

• duplicates: ARROW-5318 [Python] pyarrow hdfs reader overrequests
• links to: GitHub Pull Request #4402
• links to: GitHub Pull Request #4414