Ordered sharing: A new lock primitive for database systems

摘要

We propose a new lock primitive called ordered sharing that allows increased concurrency in database systems. A generalized two phase locking protocol is developed that may employ locks with the standard shared and non-shared relationships as well as the proposed ordered shared relationships between locks. The paper then addresses the reliability and performance issues of the proposed protocol. We show that ordered sharing results in a set of protocols that are optimal in both their reliability and concurrency aspects. A simulation study demonstrates that ordered sharing results in improved performance in database systems. The general applicability of the new primitive is further demonstrated by using it in several representative database environments.