Two Phase Commit Protocol (2PC) ■ Execution of the protocol is initiated by the coordinator after the last step of the transaction has been reached. The protocol involves all the local sites at which the transaction executed Protocol has two phases Let T be a transaction initiated at site S,and let the transaction coordinator at S;be C Database System Concepts-7th Edition 23.7 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 23.7 ©Silberschatz, Korth and Sudarshan th Edition Two Phase Commit Protocol (2PC) ▪ Execution of the protocol is initiated by the coordinator after the last step of the transaction has been reached. ▪ The protocol involves all the local sites at which the transaction executed ▪ Protocol has two phases ▪ Let T be a transaction initiated at site Si , and let the transaction coordinator at Si be Ci