HP Labs Technical Reports

Maintaining Consistency of Client-Cached Data

Wilkinson, Kevin; Neimat, Marie-Anne



Abstract: This paper addresses the problem of cache consistency in a client-server database environment. We assume the server provides shared database access for multiple client workstations and that client workstations may cache a portion of the database. Our goal is to investigate techniques to maintain the consistency of the client cache and to improve server throughput. We propose a new cache consistency algorithm for client caches. The algorithm is a simple extension to two-phase locking that requires three additional lock modes on the server. For comparison, we devised a second cache consistency algorithm based on notify locks. A simulation model was developed to analyze the performance of the server under the two cache consistency algorithms and under non-caching two-phase locking. The results are that both consistency algorithms improve server performance over basic two-phase locking. The notify locks algorithm has the best peak performance but the cache locks algorithm has more stable performance under high server load.

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