Which operation removes old files not referenced by the Delta table log?

• A. OPTIMIZE
• B. lakehouse shortcuts
• C. V-ORDER
• D. VACUUM

Answer: (D)

Delta Lake uses a transaction log to track which data files belong to a table. VACUUM is the operation that physically deletes old data files that are no longer referenced by the Delta table log, after a retention period. This cleanup helps reclaim storage and keep the data lake tidy, while still allowing time travel and rollback within the retention window. The default retention is typically seven days, but you can adjust it as needed.

The other options don’t remove old files: OPTIMIZE focuses on rewriting and compacting files to improve performance; V-ORDER reorders data within files for faster reads; lakehouse shortcuts relate to metadata/access patterns rather than deleting data.