AbstractIn this paper, we focus on the temporary return of data values that are incorrect for given transactional semantics that could have catastrophic effects similar to those in parallel and discrete event simulation systems. In many applications using online transactions processing 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 is visible to some reactive entity. In light of the avoidance of risk in this approach, we propose a risk‐free multiversion temporally correct concurrency‐control algorithm. We discuss the algorithm, its implementation and report on the performance results of simulation models using a cluster of workstations. Copyright © 2004 John Wiley & Sons, Ltd.