Locking Timestamps versus Locking Objects

Abstract

We present multiversion timestamp locking (MVTL), a new genre of multiversion concurrency control algorithms for serializable transactions. The key idea behind MVTL is simple: lock individual timestamps instead of locking objects. After presenting a generic MVTL algorithm, we demonstrate MVTL's expressiveness: we give several simple MVTL algorithms that address limitations of current multiversion schemes, by committing transactions that previous schemes would abort, by avoiding the problems of serial aborts or ghost aborts, and by offering a way to prioritize transactions that should not be aborted. We give evidence that, in practice, MVTL-based algorithms can outperform alternative concurrency control schemes.