Research On The Clustering-based Concurrency Control Algorithm For Database Transactions

Concurrency control is a mechanism that database systems provide to allow transactions to be executed at the same time while enforcing isolation.The concurrency control algorithm is key to performance of a database system.However,different concurrency control algorithms have different strengths and weaknesses,making each of them fits only for some types of workloads,while performs unsatisfactorily for others.As a result,the user will have to make assumptions about the workloads before choosing the concurrency control algorithm to achieve the best performance.To overcome this limitation,this paper proposes a scheme,called transaction clustering,to decide the best isolation mechanism for any given pair of transactions automatically.Based on transaction clustering,we further develop the Clustering-based Concurrency Control algorithm,or C3 for short,which combines the pessimistic and the optimistic concurrency control algorithms to get the best of both worlds while mitigating their performance bottlenecks at the same time.Both theoretical and empiracal analysis show that the C3 algorithm can achieve better performance compared to both the pessimistic and the optimsitic algorithms in highconflict workloads.