Abstract
In a distributed detebase manesement system, when several transections are processed raralletl, a concurrency control mechaniom is required maintoin the consistency of a detebase. In this thesis, problems without any concurrency control are prsented first, Than some concurrencs control alsorithme are calssified into three cataloss and discussed separately, Finally, a comparison on these alsorithme is discussed. In addition, the influence of lock arenularity to the renformance of locking alsorithms is reviewed.