Leases A lease is a lock that is granted for a specific period of time If a process needs a lock even after expiry of lease,process can renew the lease But if renewal is not done before end time of lease,the lease expires, and lock is released Leases can be used to that there is only one coordinator for a protocol at any given time Coordinator gets a lease and renews it periodically before expire If coordinator dies,lease will not be renewed and can be acquired by backup coordinator Database System Concepts-7th Edition 23.32 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 23.32 ©Silberschatz, Korth and Sudarshan th Edition Leases ▪ A lease is a lock that is granted for a specific period of time ▪ If a process needs a lock even after expiry of lease, process can renew the lease ▪ But if renewal is not done before end time of lease, the lease expires, and lock is released ▪ Leases can be used to that there is only one coordinator for a protocol at any given time • Coordinator gets a lease and renews it periodically before expire • If coordinator dies, lease will not be renewed and can be acquired by backup coordinator