为确保事务操作的正确并发,DBMS 将使用 Lock Manager (LM) 来控制何时允许事务访问数据项。 LM 的基本思想是它维护一个由当前 active 事务持有的 lock 的内部数据结构。 事务在允许访问数据项之前要向 LM 发出锁请求。 LM 将选择:授予该事务锁 / block 该事务 / abort 该事务。 在你的实现中,整个系统将有一...
Thus, locks need to be complemented by a concurrency control protocol. Two-Phase Locking (2PL) Two-Phase locking (2PL) is a pessimistic concurrency control protocol that uses locks to determine whether a transaction is allowed to access an object in the database on the fly. In 2PL, all ...
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Kuznetsov, “XDGL: XPath-Based Concurrency Control Protocol for XML Data,” Lecture Notes in Computer Science, Vol. 3567, pages. 145-156, 2005. :Pleshachkov P, Chardin P, Kusnetzov S. XDGL: XPath-based concurrency control protocol for XML data. Proceedings of 22nd British National ...