In distributeddatabase System (DBS) and multitasking system, the occurrence of deadlocks is one of the most serious problems. If a site request for a resource that is already in the another site which is waiting for ...
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In this paper a net model for decentralized control of user accesses to a distributeddatabase is proposed and developed in detail for a restricted case. Predicate/transition-nets, a first-order extension of Petri net...
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For better protection of distributedsystems, two well-known techniques are: checkpointing and rollback recovery. While failure protection is often considered a separate issue, it is crucial for establishing better se...
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This paper studies Trust in real-time distributed database systems. High availability and fault-tolerance are important aspects of these real-time systems and are commonly achieved by replication. Different existing r...
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Recent advancement of computer network systems makes the provision of distributed database systems attractive, and as such, they have more and more come to be the topic of discussion. These systems permit users to use...
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distributed database systems can yield significant cost and performance advantages over centralized systems for geographically distributed organizations. The efficiency of a distributeddatabase depends primarily on t...
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In designing distributeddatabases, data allocation is one of the key design issues. Some advantages of optimal data allocation are reducing cost, increasing performance and availability. However, because of that most...
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In designing distributeddatabases, data allocation is one of the key design issues. Some advantages of optimal data allocation are reducing cost, increasing performance and availability. However, because of that most of current data allocation techniques have considered only cost and performance, those techniques cannot maintain the availability, and are not proper to the system requiring high-availability. In this paper, we suggested the TCOP(Transaction COmmit Probability) model, which is a new availability model considering multiple path failures occurred during the execution time for distributed transactions. In addition, we proposed a data allocation technique using the genetic algorithms, which can maintain the availability and minimize the processing cost. According to the experimental results, the proposed TCOP model and data allocation technique have shown improvement of the data availability.
Virtual Time is the fundamental concept in optimistic synchronization schemes. In this paper, we investigate the efficiency of a distributeddatabase management system, synchronized by virtual time using a LAN connect...
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ISBN:
(纸本)3540649522
Virtual Time is the fundamental concept in optimistic synchronization schemes. In this paper, we investigate the efficiency of a distributeddatabase management system, synchronized by virtual time using a LAN connected collection of SPARCS. To the best of our knowledge, there is little data reporting VT performance in DDBMS. The experimental results are compared with a multiversion timestamp ordering (MVTO) concurrency control method, a widely used technique in distributeddatabases, and approximately 25-30% reduction in the response time is observed when using the VT synchronization scheme. Our results demonstrate that the VT synchronization approach is a viable alternative concurrency control method for distributed database systems and outpforms MVTO one.
The advent of high-speed networks will enable the deployment of data-server systems currently used in local-area networks, over wide-area networks. The users of these systems will have the same high expectations with ...
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The advent of high-speed networks will enable the deployment of data-server systems currently used in local-area networks, over wide-area networks. The users of these systems will have the same high expectations with respect to performance parameters such as the transaction throughput, response time and system reliability as in the case of local-area networks. Thus, it is important to study the performance of existing distributeddatabase protocols in the new networking environment, identify the performance bottlenecks and develop protocols that are capable of taking advantage of the high speed networking technology. As a first step, in this paper we examine the scalability of the server-based two-phase locking (s-2PL) protocol, and discuss three optimizations which allow the s-2PL protocol to be tailored for high-speed wide-area network environments where the size of the message is less of a concern than the number of rounds of message passing. These optimizations, collectively called the group two-phase locking (g-2PL) protocol, reduce the member of rounds of message passing by grouping lock grants, client-end caching and data migration. In a simulation study, 20-25% improvement in the response time of the g-2PL protocol over that of the s-2PL protocol was observed.
In this paper, we present an integrated concurrency control approach for a multidatabase system that overcome some weaknesses of the previous approaches. The presented method allows local schedulers, based on differen...
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ISBN:
(纸本)0780312333
In this paper, we present an integrated concurrency control approach for a multidatabase system that overcome some weaknesses of the previous approaches. The presented method allows local schedulers, based on different strategies and with different requirements, to be efficiently and effectively, integrated into one interoperable structure.
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