一种实时数据库系统的多版本两段锁的并发控制协议

详细讨论了与并发控制有关的实时数据和实时事务的各种特征以及分类，主要包括：实时数据对象可分为映像对象、导出对象和不变对象；实时事务按功能分类可分为数据接收事务、数据处理事务和控制事务；数据接收事务和控制事务是硬实时事务，是不能等待和阻塞的．然后，根据这些特点对传统数据库系统的多版本并发控制机制进行了扩展，提出了实时数据库系统的多版本两段锁及多版本带夭折两段锁协议，且证明了两者都是冲突可串行化的．前者对于只读事务是没有延迟的，对于硬实时事务的延迟也很小；后者对硬实时事务不产生任何延迟，这两个协议都能较好地保证实时事务和实时数据的定时限制．

Concurrency Control Protocol of MultiversionTow-phase Locking in Real-time Database Systems

All kind of timing properties and classification about real-the data and transaction associating with concurrency control are discussed. Real-time data objects classify image objects, derived objects and invariant objects. Real-time transactions cop data receiving transactions, data processing processing and control transactions by functions Transactions of data receiving and control are hard real-time trans actions which are not wait and blocked. Second,multiversion Schemes of traditional database system according to those properties are expanded, multiversion two-phase locking protocol and multiversion phase with aborting protocol which are conflict serializable in read-time database system are presented. The former has not delay for only-read transactions, and has littile delay for hard real-time transactions, the later has no delay for hard read-time transaction. Two protocols of concurrency control can ensure tim - ing constraints of "real-time transactions and data well.