The .xdf format is a binary file format that:
- Stores data in blocks for efficient reading of arbitrary columns and contiguous rows
- Contains associated metadata, such as variable names, descriptions, and data storage types
- Supports a richer set of data storage types than R (eight types of integers, two types of floating point numbers
- Writes data blocks of rows so that data processing can be optimized
- Processes data in chunks (groups of blocks)
- Optimizes the block sizes depends on individual computer bandwidth for I/O
- Contains meta information at the end of the .xdf file rather than the beginning for easy updating