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Journal of Industrial and Production Engineering 2000年第6期17卷 643-650页

作者： H. L. Li[a] H. C. Shu[a] T. S. Lee[a] [a]Institute of Information Managemet National Chiao Tung University

摘要摘要隨著網際網路的普及，資料可於組織內透過網路連結，將分散於各地的資料庫伺服器連結；亦即可在組織內架設一分散式資料庫，提供使用者多元化的查詢服務。而其最關鍵問題即爲如何在數個資料庫中決定檔案的儲存位置，使使用者的... 详细信息

摘要摘要隨著網際網路的普及，資料可於組織內透過網路連結，將分散於各地的資料庫伺服器連結；亦即可在組織內架設一分散式資料庫，提供使用者多元化的查詢服務。而其最關鍵問題即爲如何在數個資料庫中決定檔案的儲存位置，使使用者的總査詢時間爲最短。本研究提出一資料檔配置模式，在有限的空間資源及允許資料檔多重備份的情況下，決定網路中最佳的資料檔配置策略。此模式的計算效率比現有方法[2][4][5]高出許多。AbstractWith popularity of Internet, data can be linked with distributed databases by building a distributed database. One of most critical problems in distributed database design is to decide the locations of several DBs thus to minimize the total time of users’ *** study proposes a data file allocation model under limited resources. The proposed model has better computational efficiency comparing with current models [2][4][5].

关键词：分散式資料庫資料檔配置 distributed database system data allocation

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应用于舰队的多库系统模型

应用于舰队的多库系统模型

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第十七届全国数据库学术会议

作者：叶常春国防科大计算机学院

1引言分布式数据库系统的理论和技术研究开展了多年,也取得了很多成果,但业界早期期望的分布式数据库系统软件产品并没有出世,主要原因是"大而全"的目标使得实现十分困难。C/S结构的数据库系统目前成为主流产品,特点就是简单... 详细信息

1引言分布式数据库系统的理论和技术研究开展了多年,也取得了很多成果,但业界早期期望的分布式数据库系统软件产品并没有出世,主要原因是"大而全"的目标使得实现十分困难。C/S结构的数据库系统目前成为主流产品,特点就是简单实用。结合实际应用背景开发分布式数据库系统是一条可行之路:舍弃一些实际应用并不要求的目标或者降低若干指标,关注应用的中心目标,利用现有分布式数据库系统研究成果和数据库系统软件产品技术实现一个分布式数据库系统,它优于集中式数据库系统的简单拼凑,能更好地支持数据共享和集成,同时使得系统实现变得可行。

关键词： multi-database distributed database system hierarchical model

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Optimising the distributed execution of join queries in polynomial time

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COMPUTERS & MATHEMATICS WITH APPLICATIONS 1999年第3期37卷 105-126页

作者： Reid, DJ Def Sci & Technol Org Div Informat Technol Salisbury SA 5108 Australia

It is proposed that an optimal strategy for executing a join query in a distributed database system may be computed in a time which is bounded by a polynomial function of the number of relations and the size parameters of the network. The solution so unveiled considers both the transmission costs and the processing costs incurred in delivering the required result to the user that issued the query. The query specifies that several relational tables are to be coalesced and presented to the appropriate user. Undertaking this task demands the utilisation of limited system resources, so that a strategy for fulfilling the request that imposes minimal cost to the system should be devised. Both the processor sites, and the communications links that interconnect them, are utilised;an optimal strategy is one that minimises a weighted sum of processing and data transmission costs. An integer linear programming model of this problem was originally proposed in [Ij;however, no suggestion was given as to how this model might be efficiently solved. By extending the earlier analysis, the recursive nature of the join computation is revealed. Further investigations then produce a modified relationship amenable to algorithmic solution;the resultant procedure has polynomial time and space requirements. (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词： distributed database system dynamic program information system integer linear program join query optimisation

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database migration: A new architecture for transaction processing in broadband networks

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1998年第5期10卷 839-854页

作者： Hara, T Harumoto, K Tsukamoto, M Nishio, S Osaka Univ Grad Sch Engn Dept Informat Syst Engn Osaka 5650871 Japan

Due to recent developments in network technologies, broader channel bandwidth is becoming prevalent in worldwide networks. As one of the new technologies making good use of such broadband channels, dynamic relocation of databases through networks, which we call database migration, will soon be used in practice asa powerful and basic database operation. We propose two transaction processing methods to take advantage of database migration in broadband networks. These methods choose the most efficient transaction processing method between the conventional method, based on the two-phase commit protocol, and our method, using database migration. We also propose a concurrency control mechanism and a recovery mechanism for our proposed methods. Simulation results are presented comparing the performance of our proposed methods and the conventional transaction processing method based on the two-phase commit protocol. The results demonstrate that the effective use of database migration produces better performance than the conventional method.

关键词： database migration broadband network distributed database system transaction processing concurrency control

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File allocation designs for distributed multimedia information networks

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IEICE TRANSACTIONS ON COMMUNICATIONS 1998年第8期E81B卷 1647-1655页

作者： Nakaniwa, A Ebara, H Okada, H Kansai Univ Fac Engn Suita Osaka 5648680 Japan

In this paper, we study the optimal allocation of multimedia files in distributed network systems. In these systems, the files are shared by users connected with different servers geographically separated, and each file must be stored in at least one of servers. Users can access any files stored in any servers connected with high-speed communication networks. Copies of the files accessed frequently are to be stored in several servers that have databases. So, it is one of the most important problems how to assign the files to servers in view of costs and delays. Considering these problems in heterogeneous network environments, we present a new system model that covers wide range of multimedia network applications like VOD, GALS, and so on. In these systems, it is obvious that there is trading-off relationship between costs and delays. Our objective is to find the optimal file allocation such that the total cost is minimized subject to the total delay. We introduce a 0-1 integer programming formulation for the optimization problem, and find the optimal file allocation by solving these formulae.

关键词： distributed processing distributed database system optimal file allocation video on demand multimedia information network heterogeneous network

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EVALUATING MULTIPLE JOIN QUERIES IN A distributed database system

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MATHEMATICAL AND COMPUTER MODELLING 1995年第7期21卷 83-98页

作者： REID, DJ Distributed Systems Technology Centre Department of Computer Science The University of Queensland St. Lucia Queensland 4072 Australia

It is proposed that the execution of a set of join queries in a distributed environment should be considered cooperatively, rather than as a set of separate requests. With this understanding, a model of multiple query execution in the form of a linear integer program is offered. Several requests are issued to the distributed database management system, each specifying the collation of information comprised of a number of logically distinct data sets, or relations, and dispersed across the sites of a distributed system. Performing these tasks demands the usage of limited resources, so that efficient management commands the smallest additional imposition possible. Both processors and the data communication devices that interconnect them are exploited;an optimal strategy is defined to be one that minimizes a weighted sum of the costs of computation and those of information exchange incurred in resolving the group of queries. Previous models of join query evaluation would regard each individual query in isolation, to produce a sequence of independent execution strategies, one correspondingly for every request. By instead permitting multiple utilization of intermediate computations, any overlap between these queries can be exploited to further reduce the total demand placed on the system as a whole. Through investigations into the character of a number of interacting join computations, performed at a single site in isolation, an earlier single query model [1] can be extended to facilitate the cooperative execution of an entire group.

关键词： distributed database system INTEGER PROGRAM JOIN QUERY RELATIONAL database

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ALLOCATING RELATIONS IN A distributed database system

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MATHEMATICAL AND COMPUTER MODELLING 1995年第8期22卷 33-47页

作者： REID, DJ ORLOWSKA, M Department of Computer Science The University of Queensland St. Lucia Queensland 4072 Australia

A model is proposed that allocates tables of a relational database to the sites of a distributed system in order that the total cost of executing a given collection of join queries is minimized. This model is presented in the convenient form of an integer linear program. Each individual query specifies that several logically distinct data sets, or relations, are to be amalgamated and presented to the particular user that issued the request. Performing this task requires the utilization of limited system resources;both processors, and the communications facilities that interconnect them, may be used. An optimal strategy for executing a single query is, therefore, defined to be one that minimizes a weighted sum of the costs of computation, and those of information interchange, incurred during the computation. One particular model, appearing in [1], conforms to this philosophy, and so forms the basis for further investigations. The total cost of executing an entire group of such queries depends upon the way in which the relevant information is allocated to the sites of the network. Several copies of any particular relation may be dispersed across the network;the replication of data increases its availability, and potentially decreases the costs of answering the given requests. However, only limited storage capacities are available, and increased replication commands greater overheads in maintaining consistency. An optimization program is developed to design a data allocation plan that achieves a minimal total cost for the execution of a given group of requests, while maintaining restraints on the levels of data replication considered permissible.

关键词： distributed database system INTEGER PROGRAM JOIN QUERY RELATIONAL database

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EXECUTING JOIN QUERIES IN AN UNCERTAIN distributed ENVIRONMENT

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MATHEMATICAL AND COMPUTER MODELLING 1995年第3期22卷 9-23页

作者： REID, DJ Distributed Systems Technology Centre Department of Computer Science The University of Queensland St. Lucia Queensland 4072 Australia

The uncertainty inherent in the distributed environment poses new challenges to the efficient utilization of system resources in managing database transactions. In response to this realization, the execution of a join query in a system with probabilistic resource and cost parameters is contemplated, leading to the development of stochastic programming models. Information in the form of relational tables and scattered amongst the sites of a distributed database system is to be collated and presented to the appropriate user, in response to an issued request. Performing this task demands the usage of limited resources;the ultimate goal is the determination of an execution strategy incurring minimal cost to the system. The actual state of any network component at the moment of its exploitation cannot be exactly ascertained in advance. Any interrogation of a distant element must be communicated by the network, and this involves a delay, as perceived by the questioner, during which the state of the system may change. Indeed, the time at which a task assigned to any particular component cannot itself be precisely predicted, even if the future state of the component could be known definitively. By considering the uncertain nature of the distributed environment, the earlier model of join query evaluation presented in [1] can be modified in different ways to account for system parameters known only in a stochastic sense. This new level of subjectivity is a revelation of the many different attitudes that may be taken towards the chance of infeasibility in the solution, for the major issue in dealing with uncertainty is the choice of an appropriate measure of risk.

关键词： distributed database system INTEGER PROGRAMMING JOIN QUERY RELATIONAL database STOCHASTIC PROGRAMMING

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AN OPTIMAL STATIC PESSIMISTIC SCHEME FOR FAULT TOLERANT distributed database systemS

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International Journal of Reliability, Quality and Safety Engineering 1994年第3期1卷 365-378页

作者： HOANG PHAM DAVID POTOSKI Department of Industrial Engineering Rutgers University P.O. Box 909 Piscataway NJ 08855 USA

A distributed database system often replicates data across its servers to provide a fault-resistant application, which maximizes server availability. Various replication control protocols have been developed to ensure data consistency. In this paper, we develop optimal design methods for the quorum-consensus replication protocol, which (1) maximizes availability of the distributed database systems and (2) minimizes the total system cost by calculating the optimal read quorum and the optimal number of system servers. Several numerical examples and applications are provided to illustrate the results.

关键词： distributed database system Static Pessimistic Scheme system Availability Quorum-Consensus Replication Protocol Optimal Design

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OPTIMAL distributed EXECUTION OF JOIN QUERIES

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COMPUTERS & MATHEMATICS WITH APPLICATIONS 1994年第11期27卷 27-40页

作者： REID, DJ Distributed Systems Technology Centre Department of Computer Science The University of Queensland St. Lucia Queensland 4072 Australia

It is proposed that the execution of a chain query in a distributed system can be usefully and appropriately modeled as an integer linear program. In response to a user request, information in the form of relational tables scattered across the network is to be combined and made available to the user. The formulation initially attained by considering the behavior of the distributed system in processing such a query is then reduced by removing redundant linear constraints, to produce a model of minimal transmission cost execution. In view of varying properties displayed by the possibly many optima of this problem, further attention is devoted to discriminating between them. By perturbing the objective function, those solutions requiring fewer network transmissions can be favored at the expense of equal-cost, but more complicated, strategies. This includes those strategies that may specify the transmission of a relation around a cycle;when the costs of transmission between sites forming the cycle are zero, such a solution might otherwise be optimal. Many different ways have been devised to solve programs having some number of variables restricted to taking only integer values in some interval, and virtually any of these might be used to solve the join query model. One possible method, using a tree-search approach, is discussed here.

关键词： distributed database system INTEGER LINEAR PROGRAM JOIN QUERY SIMPLEX METHODS TREE-SEARCH ALGORITHM

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