Real-Time Data Semantics and Similarity-Based Concurrency Control

AbstractÐThis paper formalizes the concept of similarity which has been used on an ad hoc basis by application engineers to provide more flexibility in concurrency control. We show how the usual correctness criteria of concurrency control, namely, final-state, view, and conflict serializability, can be weakened to incorporate similarity. We extend the weakened correctness criteria in [16] for real-time applications which may run continually, have concurrent transaction executions, or skip unimportant computations. A semantic approach based on the similarity concept is then taken to propose a sufficient condition for scheduling real-time transactions without locking of data. Index TermsÐConcurrency control, schedule correctness, real-time database, serializability, similarity. æ