The Two-Phase Locking Protocol A protocol which ensures conflict- serializable schedules. Phase 1:Growing Phase Transaction may obtain locks Transaction may not release locks Phase 2:Shrinking Phase Transaction may release locks Transaction may not obtain locks Time The protocol assures serializability.It can be proved that the transactions can be serialized in the order of their lock points (i.e.,the point where a transaction acquired its final lock). Database System Concepts-7th Edition 18.9 @Silberschatz,Korth and SudarshanDatabase System Concepts - 7 18.9 ©Silberschatz, Korth and Sudarshan th Edition The Two-Phase Locking Protocol ▪ A protocol which ensures conflict￾serializable schedules. ▪ Phase 1: Growing Phase • Transaction may obtain locks • Transaction may not release locks ▪ Phase 2: Shrinking Phase • 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 (i.e., the point where a transaction acquired its final lock). Time Locks