分布式数据库中的一种并发控制改进算法

针对分布式数据库系统的并发控制，本文引入了冲突类的思想，提出了一种对EWL算法的改进并发控制算法。冲突类方法可以保证事务调度的串行性，因为冲突的事务被完全串行化。采用这种方法永远不会碰到死锁。而基于锁的并发控制则有可能发生死锁。因此本算法主要基于冲突类，如果冲突类方法失效，则采用EWP和PSL。本算法充分融合了冲突类、乐观算法、悲观算法去弥补它们各自的缺点，因此具有一定实用性。

an Improved Algorithm of Concurrency Control in Distributed Database Systems

In view of the distributed database concurrency control, this paper has introduced the idea of conflict class, proposed an improved concurrency control algorithm on the basement of EWL algorithm. The conflict class method may generate s serializable schedule for the execution of pending transactions, because the conflict transactions completely serializable. If we use this method we will never be able to meet the deadlock, but locking-based concurrency control have the possibility to meet deadlock. Therefore this algorithm is mainly based on the conflict class, if the conflict class method expires, then uses EWP and PSL. This algorithm fully fused the conflict class, the optimistic algorithm, the pessimistic algorithm to make up theirs shortcomings, so it has certain usability.