PERFORMANCE ANALYSIS OF UPDATE SYNCHRONIZATION ALGORITHMS FOR DISTRIBUTED DATABASES.

摘要

One of the most critical problem in the implementation of distributed databases is that of concurrency control. The problem is to preserve the consistency of data (that may otherwise be destroyed by concurrent accesses). One of the major goals in the research of distributed databases is to develop design methodology and guidelines for designing good concurrency control methods for a given system environment. In this thesis, we have set out to approach the goal by analyzing some of the concurrency control schemes in an effort to understand their relative merits, investigate the sensitivity of the performance to different parameters, and to provide some guidelines for designing resilient concurrency algorithms for distributed databases.;Several update synchronization algorithms are modelled and analyzed in this dissertation. Algorithms investigated in this dissertation include a resilient centralized locking algorithm, some distributed algorithms using timestamps, and some algorithms using clock messages in addition to timestamps. Results from the analysis allowed us to pinpoint inefficiency and suggest some new algorithms.