Implementation of Locking A lock manager can be implemented as a separate process to which transactions send lock and unlock requests The lock manager replies to a lock request by sending a lock grant messages (or a message asking the transaction to roll back,in case of a deadlock) The requesting transaction waits until its request is answered The lock manager maintains a data-structure called a lock table to record granted locks and pending requests The lock table is usually implemented as an in-memory hash table indexed on the name of the data item being locked Database System Concepts-5th Edition,Oct 5,2006 16.14 ©Silberschat乜，Korth and SudarshanDatabase System Concepts - 5 16.14 ©Silberschatz, Korth and Sudarshan th Edition, Oct 5, 2006 Implementation of Locking A lock manager can be implemented as a separate process to which transactions send lock and unlock requests The lock manager replies to a lock request by sending a lock grant messages (or a message asking the transaction to roll back, in case of a deadlock) The requesting transaction waits until its request is answered The lock manager maintains a data-structure called a lock table to record granted locks and pending requests The lock table is usually implemented as an in-memory hash table indexed on the name of the data item being locked