移动数据库系统乐观事务处理策略

在移动数据库系统中，计算平台的移动性，频繁的断接性以及长事务等特性使得传统的事务处理模式不再适用，为了解决移动数据中的事处处理问题，提出了一种新的移动事务处理模型－乐观两阶段提交移动事务模型（O2PC－MT），该模型采用乐观并发控制与两阶段提交协议相结合的方法，对移动事务的长事务特性提供了灵活与有效的支持，此外，该模型允许移动计算机分多发送中务操作，且在事务执行过程中可以任意移动，从而提供了对交互式事务及随意移动性的支持，实验结果表明，与基于两段锁协议及其变形的其它移动事务处理模型相比，O2PC－MT提高了系统的事务吞吐率并改善了系统的总体性能。

OPTIMISTIC TRANSACTION PROCESSING IN MOBILE DATABASE SYSTEMS

In mobile database systems, new features such as mobility, disconnection and long-lived transactions make traditional transaction processing schemes no longer suited. To solve this problem, a new mobile transaction model, O2PC-MT, is proposed in this paper. The O2PC-MT combines optimistic concurrency control with two-phase locking in mobile transaction processing, and utilizes two-phase commit protocol for the global commitment of mobile transactions. In this way, the O2PC-MT provides an effective support for the long-lived transaction property. In addition, mobile computers are allowed to submit mobile transactions in multiple request messages and to move arbitrarily during transaction execution. Therefore, the O2PC-MT provides a flexible support for interactivity and arbitrary mobility. The experiment results show that the O2PC-MT model outperforms the previously proposed mobile transaction models that utilize the two-phase locking or its variants for mobile transaction processing.