This paper introduces a multi-granularity locking model (MGL) for concurrency control in object-oriented database system briefiy, and presents a MGL model formally. Four lockingscheduling algorithms for MGL are propos...This paper introduces a multi-granularity locking model (MGL) for concurrency control in object-oriented database system briefiy, and presents a MGL model formally. Four lockingscheduling algorithms for MGL are proposed in the paper. The ideas of single queue scheduling(SQS) and dual queue scheduling (DQS) are proposed and the algorithm and the performance evaluation for these two scheduling are presented in some paper. This paper describes a new idea of thescheduling for MGL, compatible requests first (CRF). Combining the new idea with SQS and DQS,we propose two new scheduling algorithms called CRFS and CRFD. After describing the simulationmodel, this paper illustrates the comparisons of the performance among these four algorithms. Asshown in the experiments, DQS has better performance than SQS, CRFD is better than DQS, CRFSperforms better than SQS, and CRFS is the best one of these four scheduling algorithms.展开更多
Being an important part of Information System, Database Security has absorbed much attention fordecades. First, we bring forth the Database Security's contents, properties of data: sensitivity, integrity and avail...Being an important part of Information System, Database Security has absorbed much attention fordecades. First, we bring forth the Database Security's contents, properties of data: sensitivity, integrity and availabil-ity. Several access control models to guarantee these properties are described in this paper. Due to the challengesbrought by advanced DBMSs such as OODBMS and ADBMS, we also discuss some security topics in these fields. Atthe end of this paper, the encryption control and inference control are reviewed together with some trend of thedatabase security technology in the future.展开更多
文摘This paper introduces a multi-granularity locking model (MGL) for concurrency control in object-oriented database system briefiy, and presents a MGL model formally. Four lockingscheduling algorithms for MGL are proposed in the paper. The ideas of single queue scheduling(SQS) and dual queue scheduling (DQS) are proposed and the algorithm and the performance evaluation for these two scheduling are presented in some paper. This paper describes a new idea of thescheduling for MGL, compatible requests first (CRF). Combining the new idea with SQS and DQS,we propose two new scheduling algorithms called CRFS and CRFD. After describing the simulationmodel, this paper illustrates the comparisons of the performance among these four algorithms. Asshown in the experiments, DQS has better performance than SQS, CRFD is better than DQS, CRFSperforms better than SQS, and CRFS is the best one of these four scheduling algorithms.
文摘Being an important part of Information System, Database Security has absorbed much attention fordecades. First, we bring forth the Database Security's contents, properties of data: sensitivity, integrity and availabil-ity. Several access control models to guarantee these properties are described in this paper. Due to the challengesbrought by advanced DBMSs such as OODBMS and ADBMS, we also discuss some security topics in these fields. Atthe end of this paper, the encryption control and inference control are reviewed together with some trend of thedatabase security technology in the future.
