Regarding the deletion of user records, what assurance does Delta Lake offer about deleted data in terms of permanence?

Delta Lake provides a nuanced approach to data deletion that emphasizes safety and recovery options. When records are deleted using Delta Lake's DELETE command, they are not removed from the storage immediately; instead, they are marked as deleted in the transaction log. This means that while these records are no longer visible in standard query results, they remain physically present on the underlying storage until a VACUUM operation is executed.

This design choice allows for a safeguard against accidental deletions or the need to recover data shortly after it has been deleted. The VACUUM operation is required to permanently remove the deleted files, effectively reclaiming storage space and ensuring the data is no longer retrievable. Thus, until VACUUM is performed, deleted records are still accessible, either through querying historical versions of the Delta table or by directly accessing the underlying storage if necessary. This ability to delay permanent deletion provides flexibility in data management and aids in maintaining data integrity during operations that involve potentially destructive actions.