使用pyarrow加载Parquet文件遇IOError及ArrowIOError求助

Hey there, let's break down why this specific Parquet file is throwing errors while your other similar files load just fine. Since you're new to working with Parquet, I'll walk through common issues and fixes step by step:

• Double-check the file path and existence
  The path you're using (/tmp/dt=20/09_0) might have hidden issues:

  • First, confirm the file actually exists at that location. Run a terminal command like ls /tmp/dt=20/ (Linux/macOS) or dir C:\tmp\dt=20\ (Windows) to verify the file is present.
  • Watch out for typos in the path—even a single wrong character can cause this error. If dt=20 is a partition directory, make sure the structure matches your other working files.

• Verify the file isn't corrupted
  Corruption is a common culprit, especially if the file was interrupted during writing or transfer. Test reading it directly with pyarrow (bypassing pandas) to isolate the issue:

  import pyarrow.parquet as pq
  
  try:
      # Try reading the file as an Arrow Table
      table = pq.read_table('/tmp/dt=20/09_0')
      print("Success! The file is readable with pyarrow directly.")
  except Exception as e:
      print(f"Pyarrow failed to read the file: {str(e)}")
  

  If this fails too, the file is almost certainly corrupted. You'll need to regenerate it from the original source data.

• Check for version compatibility issues
  Parquet files can have version differences, and mismatches between the library used to write the file and your current pyarrow version can cause errors. Compare metadata from a working file and the problematic one:

  import pyarrow.parquet as pq
  
  # Get metadata from a working file
  try:
      good_metadata = pq.read_metadata('/path/to/your/working/file.parquet')
      print("Working file metadata:")
      print(good_metadata)
  except Exception as e:
      print(f"Failed to read good file metadata: {e}")
  
  # Try getting metadata from the problematic file
  try:
      bad_metadata = pq.read_metadata('/tmp/dt=20/09_0')
      print("\nProblematic file metadata:")
      print(bad_metadata)
  except Exception as e:
      print(f"\nFailed to read bad file metadata: {e}")
  

  Look for differences in Parquet version, arrow version, or compression codec. If there's a big mismatch, you might need to upgrade/downgrade your pyarrow installation to match the version used to write the file.

• Inspect file permissions
  Even if other files in the same directory work, this specific file might have restricted permissions. On Linux/macOS, run ls -l /tmp/dt=20/09_0 to check if your user has read access. On Windows, right-click the file > Properties > Security to confirm your account has read permissions.

• Confirm the file is actually a Parquet file
  It's possible the file was renamed to look like a Parquet file but is actually a different format. On Linux/macOS, run file /tmp/dt=20/09_0 to check the file type. You should see output mentioning "Parquet file data".

Start with the simplest checks (path existence, permissions) first—those are often the quickest fixes. If those don't resolve it, testing with pyarrow directly will tell you if the file is corrupted. Let me know what you uncover!

内容的提问来源于stack exchange，提问作者user3476463