Many applications of object-oriented database systems demand high performance and require longer duration transactions. These requirements are contrary to one another. Two trends in modern systems can help improve the situation. Firstly, multiprocessors are becoming commonplace, and secondly, object-oriented database systems supporting multiple versions are becoming popular. Consequently, database protocols that are less prone to extensive blocking (as can be the case with the popular two-phase locking protocol) are needed in future systems. The authors' simulation studies have shown substantial performance improvements can be obtained by using multiversion protocols for database transaction management. These protocols provide higher throughput at higher levels of concurrency (which are achievable with multiprocessors) than their traditional single version equivalents.
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