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Proceedings of the 1997 International database Engineering & Applications Symposium

作者： Wu, Xuequn Weissenberg, Norbert Deutsche Telekom AG Darmstadt Germany

In this paper we present the graphical interface of the system VHDBS, which has been jointly developed by an industrial research project at the Technology Center of the German Telekom and at the Fraunhofer ISST. The VHDBS system enables the integration and interoperation of existing distributed and heterogeneous databases, which were developed independently. The graphical interface FGRAPH of VHDBS provides uniform access to distributed and heterogeneous data. The interface is based on a sophisticated design, which enables browsing on both schema and object level, and allows both query and browsing of objects. In particular, the user can move back and forth freely between query and browsing activities. Cooperative access to the data in various underlying databases is supported and platform, location and data model transparency is provided to the user.

关键词： distributed database systems

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Views and security in distributed database management systems 1st

Views and security in distributed database management system...

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1st International Conference on Extending database Technology, EDBT 1988

作者： Bertino, E. Haas, L.M. IEI-CNR Pisa Italy IBM Almaden Research Center San JoseCA United States

ISBN: (纸本)9783540190745

Views are used in database systems to present data to different applications in a form reflecting their individual needs. The view mechanism contributes to data protection, independence, and isolation. In this paper we first discuss some issues concerning distributed database security and then the design of distributed views providing security features. The following issues concerning views are discussed: represention, change, authorization, and usage. © 1988, Springer-Verlag.

关键词： distributed database systems

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Empirical evaluation of data allocation algorithms for distributed multimedia database systems

Empirical evaluation of data allocation algorithms for distr...

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Proceedings of the 1997 21st Annual International Computer Software & Applications Conference, COMPSAC'97

作者： Karlapalem, Kamalakar Ahmad, Ishfaq So, Siu-Kai Kwok, Yu-Kwong Hong Kong Univ of Science and Technology Hong Kong Hong Kong

Given a distributed multimedia database system and a set of queries as well as their frequencies from each site, the objective of a data allocation algorithm is to locate the multimedia data objects (MDOs) at different sites so as to minimize the total data transfer cost incurred in executing the queries. The data allocation problem, however, is NP-complete, and thus requires fast heuristics to generate efficient solutions. In this paper we propose three data allocation algorithms which are based on a genetic technique, an evolutionary process, and neural networks. We have implemented and evaluated these algorithms on our distributed multimedia database system test-bed. A comparison of the algorithms reveals trade-offs between their solution quality and time-complexity.

关键词： distributed database systems

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Design of a Transaction Recovery Instance Based on Bi-directional Ring Election Algorithm for Crashed Coordinator in distributed database systems

Design of a Transaction Recovery Instance Based on Bi-direct...

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World Congress on Information and Communication Technologies

作者： Dharavath Ramesh K. Chiranjeev Kumar B. Ramji Department of CSE Indian School of Mines Suryapet

ISBN: (纸本)9781467348065

In a distributed database environment, when the coordinator site (root node or process) is not working, the environment needs to choose or elect a new one in order to perform the transactional tasks. The elected coordinator takes the lead to perform the activities as well and continues the functioning. If the previous (crashed) site is recovered from the failures then again it leads the system by taking the responsibility. In this paper, a recovery instance based on bi-directional ring election algorithm for the crashed coordinator was brought up. The new algorithm for the recovered site quickly brings the state back by sending messages in parallel instances. This work shows that how the algorithm makes the recovered site faster and takes less time to make the system quickly to handle transactions normally.

关键词： distributed database systems Coordinator Site recovery Bi-directional ring Transaction

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An Optimal Novel Byzantine Agreement Protocol (ONBAP) for Heterogeneous distributed database Processing systems

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Procedia Technology 2012年 6卷 57-66页

作者： Dharavath Ramesh Chiranjeev Kumar Indian School of Mines (ISM) Dhanbad Jharkhand 826004 India

Reliability deserves utmost position in processing the transaction effectively in distributed environment. Conservatively, the problems of consensus, Byzantine Agreement, and interactive consistency are studied in a fully connected network with multi nodes (processors) in malicious failure only. Such problematic instances are re–examined with the assumption of malicious faults on the side of both the nodes. The proposed ONBAP protocol use the minimum number of message exchanges and can endure the maximum number of allowable faulty components to make each fault-free processor reach a common agreement for the cases of processor failure to reach a goal effectively.

关键词： Fault tolerance distributed database systems Agreement protocols

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Enhancing ECA rules for distributed active database systems

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2003年 2593卷 199-205页

作者： Heimrich, Thomas Specht, Günther TU-Ilmenau FG Datenbanken und Informationssysteme 98684 Ilmenau Germany Universität Ulm Abteilung Datenbanken und Informationssysteme 89069 Ulm Germany

ECA (event/condition/action) rules have been developed for central active database systems. In distributed active database systems the problem of inaccessibility of partial systems raises and thus the undecidability of ECA conditions referring to remote systems. This work proposes an enhancement of ECA rules for distributed active database systems to react also in the case of inaccessibility and undecidability. Therefore, the ECA evaluation will be enhanced to a strict function with the inaccessibility state Ω and a new alternative action AA enriches the classical ECA rules. The advantages and the usage of this approach are shown by an example of maintaining data consistency in distributed active database systems. © Springer-Verlag Berlin Heidelberg 2003.

关键词： distributed database systems

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A new approach for distributed main memory database systems: A causal commit protocol

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IEICE TRANSACTIONS ON INFORMATION AND systems 2004年第1期E87D卷 196-204页

作者： Lee, I Yeom, HY Park, T Seoul Natl Univ Dept Comp Sci Seoul 151 South Korea Sejong Univ Dept Comp Engn Seoul South Korea

distributed database systems require a commit process to preserve the ACID property of transactions executed on a number of system sites. With the appearance of main memory database system, the database processing time has been reduced in the order of magnitude, since the database access does not incur any disk access at all. However, when it comes to distributed main memory database systems, the distributed commit process is still very slow since the disk logging at several sites has to precede the transaction commit. In this paper, we re-evaluate various distributed commit protocols and come up with a causal commit protocol suitable for distributed main memory database systems. To evaluate the performance of the proposed commit protocol, extensive simulation study has been performed. The simulation results confirm that the new protocol greatly reduces the time to commit the distributed transactions without any consistency problem.

关键词： distributed database systems transaction processing main memory database distributed commit protocol

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Resolving executing-committing conflicts in distributed real-time database systems

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COMPUTER JOURNAL 1999年第8期42卷 674-692页

作者： Lam, KY Pang, CL Son, SH Cao, JN City Univ Hong Kong Dept Comp Sci Kowloon Hong Kong Peoples R China Univ Virginia Dept Comp Sci Charlottesville VA 22903 USA Hong Kong Polytech Univ Dept Comp Kowloon Hong Kong Peoples R China

In a distributed real-time database system (DRTDBS), a commit protocol is required to ensure transaction failure atomicity, If data conflicts occur between executing and committing transactions, the performance of the system may be greatly affected, In this paper, we propose a new protocol, called deadline-driven conflict resolution (DDCR), which integrates concurrency control and transaction commitment management for resolving executing and committing data conflicts amongst firm real-time transactions, With the DDCR, a higher degree of concurrency can be achieved, as many data conflicts of such kind can be alleviated, and executing transactions can access data items which are being held by committing transactions in conflicting modes, Also, the impact of temporary failures which occurred during the commitment of a transaction on other transactions, and the dependencies created due to sharing of data items is much reduced by reversing the dependencies between the transactions, A simulation model has been developed and extensive simulation experiments have been performed to compare the performance of the DDCR with other protocols such as the Opt [1], the Healthy-Opt [2], and the base protocol, which use priority inheritance and blocking to resolve the data conflicts, The simulation results show that the DDCR can significantly improve the system performance under different workload and workload distributions. Its performance is consistently better than the base protocol and the Opt protocols in both main-memory resident and disk-resident DRTDBS.

关键词： Network protocols Data flow analysis distributed database systems Real time systems Concurrency control Computer system recovery Computer simulation Data storage equipment Deadline driven conflict resolution distributed real time database systems Real time transactions Data conflicts System performance Data storage devices Network protocols system recovery distributed database systems Conflict (Psychology) Concurrency control real-time systems Computer Simulation data flow analysis

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Accordion: Elastic Scalability for database systems Supporting distributed Transactions

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PROCEEDINGS OF THE VLDB ENDOWMENT 2014年第12期7卷 1035-1046页

作者： Serafini, Marco Mansour, Essam Aboulnaga, Ashraf Salem, Kenneth Rafiq, Taha Minhas, Umar Farooq Qatar Comp Res Inst Ar Rayyan Qatar Univ Waterloo Waterloo ON Canada Amazon Com Seattle WA USA IBM Res Almaden San Jose CA USA

Providing the ability to elastically use more or fewer servers on demand (scale out and scale in) as the load varies is essential for database management systems (DBMSes) deployed on today's distributed computing platforms, such as the cloud. This requires solving the problem of dynamic (online) data placement, which has so far been addressed only for workloads where all transactions are local to one sever. In DBMSes where ACID transactions can access more than one partition, distributed transactions represent a major performance bottleneck. Scaling out and spreading data across a larger number of servers does not necessarily result in a linear increase in the overall system throughput, because transactions that used to access only one server may become distributed. In this paper we present Accordion, a dynamic data placement system for partition-based DBMSes that support ACID transactions (local or distributed). It does so by explicitly considering the affinity between partitions, which indicates the frequency in which they are accessed together by the same transactions. Accordion estimates the capacity of a server by explicitly considering the impact of distributed transactions and affinity on the maximum throughput of the server. It then integrates this estimation in a mixed-integer linear program to explore the space of possible configurations and decide whether to scale out. We implemented Accordion and evaluated it using H-Store, a shared-nothing in-memory DBMS. Our results using the TPC-C and YCSB benchmarks show that Accordion achieves benefits compared to alternative heuristics of up to an order of magnitude reduction in the number of servers used and in the amount of data migrated.

关键词： distributed computer systems distributed database systems Integer programming ACID Transactions distributed computing platform distributed transaction Magnitude reduction Maximum through put Mixed integer linear program Performance bottlenecks System throughput

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EXPLOITING distributed MEDICAL IMAGE database-systems - GENERAL-CONSIDERATIONS AND IMPLEMENTATION EXPERIENCE

EXPLOITING DISTRIBUTED MEDICAL IMAGE DATABASE-SYSTEMS - GENE...

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20th Annual Meeting of Computers in Cardiology

作者： YANG, GZ BURGER, P UNDERWOOD, SR FIRMIN, DN LONGMORE, DB ROYAL BROMPTON NATL HEART & LUNG HOSP MAGNET RESONANCE UNITLONDON SW3 6NPENGLAND

ISBN: (纸本)0818654708

This paper addresses a distributed approach for medical image database systems and its implementation. Compared with a centralized approach, a distributed strategy has the advantage of fault-tolerance, ease of integration, lower network traffic and faster system response. Various practical aspects of the system design with respect to data storage hierarchy, image format, system communication and resource sharing are discussed. An implementation example which incorporates cardiac MR, CT and Nuclear Medicine imaging systems is presented. The system is based on a Novell and TC/PIP local area network. It has also been further integrated into a Hospital Information System which controls the patient registration and resource allocation.

关键词： distributed database systems

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