Real-time database technology is a new kind of technology which combines thetraditional database technology with real-time systems processing technology to offersmore capacity on the basis of traditional databases to get a more reliable response. As anew branch of database system, its applications cover almost all fields, such as financial,legal, accounting, medical records, multimedia, process control, reservation systems andscientific data analysis, etc. Real-time database system must guarantee both thetimeliness of the transaction and the time effectiveness of data. So a key issue to bestudied in the real-time database system field is how to design better real-timetransaction scheduling algorithm to ensure the real time data’s effectiveness and makethe system resource utilization minimum.In this paper, firstly, the validity issues of real-time data are systematic analyiedaround with the system resource utilization and processor load capacity. Then severalconstrains of the scheduling algorithm are discussied. And several traditional real-timetransaction scheduling algorithms to ensure the effectiveness of real-time data areanalyzed, such as One-One, Half-Half, More-Less and the deferrable schedulingalgorithm. Secondly, based on the traditional updating transactions real-time scheduling,the existing methods to ensure the effectiveness of real-time data are combined with theearliest deadline first priority assignment principle. The constraints of More-Less anddeferrable scheduling thoughts in the fixed priority are extended to ML-DP and DS-DPalgorithms in dynamic priority scheduling scenarios, and the schedulablity of these twoalgorithms are analyzed and discussed. Finally, it is shown that the DS-DP has betterschedulablity and system performance than the ML-DP, through the experiments aboutsimulation realization and performance analysis by using the CSIM simulation platform. |