DELF: Safeguarding deletion correctness in online social networks

Introduced DELF, a new framework for safeguarding data deletion correctness in online social networks. DELF enables developers to implement deletion with minimal effort through annotations rather than code, and incorporates multiple correctness validation techniques (static validation, dynamic validation heuristics, privilege escalation checks, data type validation) to prevent data retention or accidental deletion of wrong data. DELF has been deployed at Facebook, supporting billions of deletions daily by immediately hiding target objects, hiding dependent data, asynchronously traversing the data graph for point deletes, and maintaining a restoration log for recovery.