关键词: 并发控制,冲突率预测,策略选择

Abstract: Concurrency control algorithm can guarantee the correctness and consistency of the database transaction.In order to improve the efficiency of concurrent transactions,an adaptive concurrency control algorithm based on conflict-rate prediction(ACC-PRC) was proposed.The algorithm is divided into two stages:information collection and strategy selection.The information collection stage uses a priori transaction queue PTQ to guarantee the serializable execution of the transaction,and a cyclic conflict queue CQR is used to collect the transaction execution state of the system.The strategy selection stage uses the improved weighted moving average method to predict the next stage of conflict using the cyclic conflict queue,and then chooses appropriate concurrency strategies by bidirectional threshold.The algorithm maintains good transaction efficiency while the transaction arrival rate is relatively high.The results show that the integrate performance of ACC-PRC algorithm is better than that of the HCC algorithm and ADCC algorithm.

Key words: Concurrency control,Conflict-rate prediction,Strategy selection