Improvements On Dynamic Adjustment Of Serialization Order Algorithm

Real-time database system (RTDBS) is used more and more widely in daily life with its developments and researches, such as E-business, air traffic control system, telephone switch, and electricity transport. But there are still some problems unsolved in RTDBS. The problem that makes RTDBS hard to be realized is the inconsistency between deadline and consistency. The most important characteristic in RTDBS is real-time which depends on many factors. For a given system configuration, basic factors that determine performance of real-time are concurrency control algorithms for scheduling of storing data. Recently, many researchers focus on designing the concurrency control algorithms which are suitable to RTDBS. However, the current algorithms still have the problems such as wasted execution and unnecessary restart.After analyzing dynamic adjustment of serialization order algorithm, the algorithm of OCC-CPTI, which can solve problems of unnecessary restarts, is given. After studying discard conflict transaction policy, a condition virtual discard policy is given. And OCC-CPTI-CVD algorithm is given by combining the policy with OCC-CPTI. The algorithm can solve effectively problems of wasted execution.Finally, the simulations are implemented to examine the OCC-CPTI algorithm and OCC-CPTI-CVD algorithm. Comparing the miss ratio curve of the three algorithms, it is clear that OCC-CPTI algorithm and OCC-CPTI-CVD algorithm are better than the OCC-TI. The aim is achieved.