Performance of cache coherency schemes in a shared disks transaction environment

In a shared disks environment (SDE), the computing nodes are locally coupled via a high-speed network and share a common database at the disk level. To reduce the amount of expensive and slow disk I/O, each node caches database pages in its main memory buffer. This paper focuses on SDE that uses record-level locking as a concurrency control. While the record-level locking can guarantee higher concurrency than page-level locking, it may result in heavy message traffic. In this paper, we first propose a cache coherency scheme that can reduce the message traffic in the standard locking. Then the scheme is extended to the context where lock retention and lock de-escalation are adopted. Using a distributed database simulation model, we evaluate the performance of the proposed schemes under a wide variety of database workloads.