What is the purpose of V-Order and Optimize Write in Delta tables?

• A. V-Order and Optimize Write sorts data to create many small CSV files.
• B. V-Order and Optimize Write enhance Delta tables by sorting data and creating fewer, larger Parquet files.
• C. V-Order and Optimize Write do not affect file sizes.
• D. V-Order and Optimize Write sorts data only when loaded into memory.

Answer: (B)

The main idea is to improve how data is laid out on disk so queries can read less data and do fewer I/O operations. V-Order organizes the data using a space-filling curve to place rows with similar values close together on disk. This clustering makes data skipping and pruning more effective during scans, so you end up reading only the parts of the table that matter for a given filter.

Optimize Write takes that a step further by rewriting many small Parquet files into fewer, larger Parquet files, targeting an optimal file size. This reduces file overhead and fragmentation, which speeds up reads and improves write efficiency.

Together, they shape the on-disk layout to boost performance: data is sorted in a way that helps queries quickly narrow down what’s read, and the storage is consolidated into larger files to reduce overhead. This is why the option describing sorting and creating fewer, larger Parquet files is the best fit.