A performance evaluation of a temporally correct and optimistic concurrency control protocol

In this paper we focus on the temporary return of data values that are incorrect for given transactional semantics and could have catastrophic effects similar to those in parallel and discrete event simulation. In many applications using on-line transaction processing (OLTP) environments, for instance, it is best to delay the response to a transaction´s read request until it is either known or unlikely that a write message from an older update transaction will not make the response incorrect. Examples of such applications are those where aberrant behavior is too costly, and those in which precommitted data are visible to some reactive entity. In light of the avoidance of risk in this approach, we propose a risk-free multiversion temporally correct (RFMVTC) concurrency control algorithm. We discuss the algorithm, its implementation and report on the performance results of simulation models using a cluster of workstations.