Which statement best describes a typical use of VACUUM in Delta Lake?

• A. It deletes unreferenced files older than the retention policy
• B. It moves data
• C. It compresses files
• D. It duplicates data

Answer: (A)

VACUUM in Delta Lake acts as garbage collection for data files. Delta Lake tracks all data files in a transaction log, which defines the current table snapshot. When you update or delete data, new files are created while older ones may become unreferenced. VACUUM deletes those unreferenced files, but only if they are older than the retention period you specify. This frees up storage while preserving the ability to time-travel within that retention window. It doesn’t move data, compress files, or duplicate data—those are handled by other operations or processes.