Various concurrency control algorithms have been proposed for use in distributed database systems. Even, the large number of available algorithms, but the fact that distributed database systems are becoming a commercial reality, distributed concurrency control performance tradeoffs are still not well understood. In this paper, we focus on some of the important issues by studying four representa...

Commercial databases support different isolation levels to allow programmers to trade off consistency for a potential gain in performance. The isolation levels are defined in the current ANSI standard, but the definitions are ambiguous and revised definitions proposed to correct the problem are too constrained since they allow only pessimistic (locking) implementations. This paper presents new ...

In this paper, we propose a new concurrency control algorithm based on multi-agent systems which is an extension of majority protocol. Then, we suggest a clustering approach to get better results in reliability, decreasing message passing and algorithm’s runtime. Here, we consider n different transactions working on non-conflict data items. Considering execution efficiency of some different...

Many concurrency control algorithms have been proposed for use in distributed database systems. Despite the large number of available algorithms, and the fact that distributed database systems are becoming a commercial reality, distributed concurrency control performance tradeoffs are still not well understood. In this paper we attempt to shed light on some of the important issues by studying f...

In addition to maintaining consistency of the database, secure concurrency control algorithms must be free from covert channels arising due to data conflicts between transactions. The existing secure concurrency control approaches are unfair to transactions at higher access classes. In this paper, a secure two-phase locking protocol is presented, which is correct and free from covert channels. ...