【摘要】 实时数据库系统的定时限制包括数据的定时限制和事务的定时限制，一个好的并发控制协议必须要较好地满足这些定时限制。文章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。并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，提出了一种基于时间戳的多版本实时数据库系统的并发控制协议。该协议对硬实时事务不产生任何延迟，能够很好地保证实时事务和实时数据的定时限制，缺点是该并发控制协议仅是一个准一致性的协议。更多还原

【Abstract】 ： Timing constraints in real－time database systems have data timing constraints and transaction timing constraints．A good protocol of concurrency control must satisfy those timing constraints well．This paper discusses all kind of timing properties and classification about real－time data and transactions associating with concurrency control，expands multiversion schemes of traditional database system according to those properties，presents a timestamp－based multiversion protocol in read－time database system．It has no delay for hard real－time transactions and can ensure timing constraints of real－time transactions and data very well，while it has the disadvantage of quasi－consistency．更多还原