Performance evaluation of two concurrency control protocols for distributed databases with multiversioned entities

The authors evaluate and compare the performance of two concurrency control protocols for distributed databases with multiversioned entities, assuming that each transaction incrementally declares its access set from the successive parts of the preordered entities. The first protocol is called protocol proposed (PP). The second is a variant of the protocol proposed by D.P. Reed (1978), here called RP1. Performance results for these protocols are collected using simulations. Key performance issues of PP are studied and relative performance of PP and RP1 is compared. Extra memory requirement is the most important cost for PP, while the cost associated with abortion of transactions are most important for RP1. For slow communication networks, at all workloads except some range of low workloads, PP performs better than RP1. For fast networks, between low to very high workloads RP1 performs better for a range of parameters. At extremely high workloads, both perform poorly, but the higher memory requirement of PP is more tolerable than the high abortion rate of RP1. A protocol similar to PP is proposed that permits universioned entities and so does not have extra memory cost and has the advantages of PP