Concurrency Control Manager
Concurrency control manager; Lock manager; Synchronization component
The concurrency control manager (CCM) synchronizes the concurrent access of database transactions to shared objects in the database. It is responsible for maintaining the guarantees regarding the effects of concurrent access to the shared database, i.e., it will protect each transaction from anomalies that can result from the fact that other transactions are accessing the same data at the same time. Ideally, it will make sure that the result of transactions running in parallel is identical to the result of some serial execution of the same transactions. In real applications, however, some transactions may opt for lower levels of synchronization, thus trading protection from side effects of other transactions for performance. The CCM is responsible for orchestrating all access requests issued by the transactions such that each transaction receives the level of protection it has asked for. The CCM...