VACUUM

Deleted Database Records Remain Recoverable in SQLite Files Despite DELETE Operations

A standard DELETE query in SQLite removes rows from the table view but leaves the actual data intact inside the database file until pages are reused. The pragma secure_delete setting controls whether freed pages are zeroed immediately or simply marked as available. With the default setting of 0, strings containing names and credit card numbers can still be extracted using grep even after deletion. The same behavior appears in PostgreSQL through dead row versions until VACUUM runs and in MySQL InnoDB through undo logs and the binary log. The issue directly affects compliance with personal data deletion requests because backups, replicas, and analytics exports often retain the original records. Proper mitigation requires enabling secure_delete, running VACUUM after bulk deletions, or encrypting sensitive fields with per-record keys that can be destroyed on request.