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RecordIO Format (Google)

Description​

RecordIO is a binary file format developed by Google for storing sequences of records. Each record is prefixed with its length and a CRC32 checksum. RecordIO is used in various Google systems and provides efficient sequential reading of records.

File Extensions​

  • .rio - RecordIO files
  • .recordio - RecordIO files (alias)

Implementation Details​

Reading​

The RecordIO implementation:

  • Parses RecordIO format
  • Reads length-prefixed records with CRC32 checksums
  • Handles binary record data
  • Converts records to dictionaries
  • Supports streaming for large files

Writing​

Writing support:

  • Writes length-prefixed JSON records with CRC32 checksums
  • Same framing as the reader

Key Features​

  • Google format: Developed by Google
  • CRC32 checksums: Includes data integrity checks
  • Length-prefixed: Records prefixed with length
  • Nested data: Supports complex data structures
  • Streaming: Processes files record by record

Usage​

from iterable import open_iterable

# Basic reading
with open_iterable('data.rio', iterableargs={
    'value_key': 'value'
}) as source:
    for record in source:
        print(record)  # Contains record data

# Writing
with open_iterable('output.rio', mode='w') as dest:
    dest.write({'id': 1, 'payload': 'hello'})

Parameters​

  • value_key (str): Key name for record value (default: value)

Limitations​

  1. Binary format: Not human-readable
  2. CRC32 validation: Simplified CRC32 implementation
  3. Format complexity: RecordIO format can be complex
  4. Google-specific: Primarily used in Google systems

Compression Support​

RecordIO files can be compressed with all supported codecs:

  • GZip (.rio.gz)
  • BZip2 (.rio.bz2)
  • LZMA (.rio.xz)
  • LZ4 (.rio.lz4)
  • ZIP (.rio.zip)
  • Brotli (.rio.br)
  • ZStandard (.rio.zst)

Use Cases​

  • Google systems: Working with Google data formats
  • Data storage: Efficient record storage
  • Data pipelines: Processing RecordIO data
  • Sequential reading: When you need sequential record access

Error Handling​

  • Missing dependency: optional libraries raise ImportError with an install hint (pip install 'iterabledata[<extra>]' when an extra exists).
  • Write mode: read-only formats raise WriteNotSupportedError or ValueError when opened with mode="w".
  • Bad or unsupported input: may raise ValueError, OSError, or library-specific errors.
  • See Troubleshooting for decoding, detection, and engine issues.