Performance of Multiversion and Distributed Two-Phase Locking Concurrency Control Mechanisms in Distributed Databases

Abstract In this paper we have presented a detailed simulation study of a distributed multiversion and a distributed two-phase locking concurrency control mechanisms. Our experiment concentrated on measuring the effect of message overhead, read:write ratios, data partitioning and partial replication on the performance of these mechanisms. The effect of these parameters has not been investigated in any previous work. We simulated a blind-write model for two reasons: (a) all other works studied the behavior of multiversion CCMs under read-before-write model and observed a similar result and (b) the performance of any multiversion CCM has not been studied under blind-write model. A blind-write model is not unrealistic and intuitively the multiversion should provide much better performance. We observed that multiversion outperforms Wound-Wait (WW) in both partitioned and partially replicated databases. Multi-Version (MV) handles read-only and write-only transactions efficiently and after certain write percentage the throughput improves with this percentage. The message overhead progressively becomes less significant as the MPL (Multiprogramming Level) increases, indicating that in a heavily loaded system the throughput is least sensitive to message cost. We found that in the partially replicated case 50% write does not show the lowest performance as observed in the partitioned case. Index Terms Multiversion, wound-wait, blind-write, data partition, data replication, multiprogramming level, read:write ratio, conflict potential.