Distributed Deadlocks Unnecessary rollbacks may result When deadlock has indeed occurred and a victim has been picked, and meanwhile one of the transactions was aborted for reasons unrelated to the deadlock. Due to false cycles in the global wait-for graph;however,likelihood of false cycles is low. In the distributed deadlock-detection approach,sites exchange wait-for information and check for deadlocks Expensive and not used in practice Database System Concepts-7th Edition 23.31 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 23.31 ©Silberschatz, Korth and Sudarshan th Edition Distributed Deadlocks ▪ Unnecessary rollbacks may result • When deadlock has indeed occurred and a victim has been picked, and meanwhile one of the transactions was aborted for reasons unrelated to the deadlock. • Due to false cycles in the global wait-for graph; however, likelihood of false cycles is low. ▪ In the distributed deadlock-detection approach, sites exchange wait-for information and check for deadlocks • Expensive and not used in practice