The Two-Phase Locking Protocol 两段侦协议) This is a protocol which ensures conflict-serializable schedules Phase1: Growing Phase(增长阶段) x transaction may obtain locks x transaction may not release locks Phase2: Shrinking Phase(缩减阶段) x transaction may release locks x transaction may not obtain locks The protocol assures serializability. It can be proved that the transactions can be serialized in the order of their lock points封锁点(e. the point where a transaction acquired its final lock) Database System Concepts 3rd Edition 16.8 OSilberschatz, Korth and SudarshanDatabase System Concepts 3 16.8 ©Silberschatz, Korth and Sudarshan rd Edition The Two-Phase Locking Protocol （两段锁协议） This is a protocol which ensures conflict-serializable schedules. Phase 1: Growing Phase（增长阶段） transaction may obtain locks transaction may not release locks Phase 2: Shrinking Phase（缩减阶段） transaction may release locks transaction may not obtain locks The protocol assures serializability. It can be proved that the transactions can be serialized in the order of their lock points 封锁点 (i.e. the point where a transaction acquired its final lock)