Assess understanding of database concurrency control mechanisms — locking (shared/exclusive locks, two‑phase locking, deadlock detection/avoidance), optimistic concurrency control (validation, conflict detection, rollback), and multiversion concurrency control (versioning, snapshot isolation, timestamp ordering, version cleanup). Test ability to compare correctness guarantees and performance trade‑offs, identify common anomalies (dirty reads, nonrepeatable reads, phantoms, write skew), and select suitable strategies for OLTP vs OLAP; includes short schedule/isolation analysis.