Real-time transaction processing: pessimistic, optimistic, and hybrid approaches

A real-time database system (RTDBS) differs from a conventional database system because in addition to the consistency constraints of the database, timing constraints of individual transaction need to be satisfied. To provide real-time response for queries and update while maintaining the consistency of data, real-time concurrency control should involve efficient integration of the ideas from both database concurrency control and real-time scheduling. The authors proposed hybrid real-time concurrency control protocols which combine pessimistic and optimistic approaches to concurrency control in order to control blocking and aborting in a more effective manner