참조 : Wikipedia-Optimistic concurrency control optimistic concurrency control, (OCC) is a concurrency control method used in relational databases without using locking. It is commonly referred to as optimistic locking, a misnomer.Optimistic concurrency control Non-lock concurrency control 방법들 중에 하나로 Locking을 사용하지 않고 동시성 제어를 하는 방법을 Optimistic concurrency control 또는