Optimistic Locking

CORE DEFINITION

In relational database management systems, optimistic concurrency control (also known as "optimistic locking", abbreviated as "OCC") is a concurrency control method. It assumes that multi-user concurrent transactions will not affect each other during processing, and each transaction can process the part of data it affects without generating locks. Before committing data updates, each transaction first checks whether other transactions have modified the data after it was read. If other transactions have updated it, the committing transaction will roll back. Optimistic transaction control was first proposed by Professor H.T. Kung. Optimistic concurrency control is mostly used in environments with low data race and few conflicts. In such environments, the cost of occasionally rolling back transactions is lower than the cost of locking data when reading, thus achieving higher throughput than other concurrency control methods.