畢業(yè)設(shè)計(jì)(論文)外文翻譯----分布式dbms的概念與設(shè)計(jì)-其他專業(yè)-文庫吧資料
2025-01-27 05:04本頁面
【正文】 office containing details of such things as the staff who work at that location, the properties that are for rent, and the client’s whoown or wish to rent out these properties. The staff at a branch office will make local inquiries of the databases. The pany headquarters may wish to make global inquiries involving the access of data at all or a number of branches. Improved shareability and local autonomy The geographical distribution of an anization can be reflected in the distribution of the data。 The DBMS at each site can handle local applications, autonomously。 The sites are linked by a munications work。 Fragments may be replicated。 1 The Concepts and Design of Distributed DBMS 1. INTRODUCTION A major behind the development of database systems is the desire to integrate the operational data of an anization and to provide controlled access to the data. Although integration and controlled access may imply centralization, this is not the intention. In fact, the development of puter works promotes a decentralized mode of work. This decentralized approach mirrors the anizational structure of many panies, which are logically distributed into divisions, departments, projects, and so on, and physically distributed into offices, plants, factories, where each nit maintains its own operational data. The shareability of the data and the efficiency of data access should be improved by the development of a distributed database system that reflects this anizational structure, makes the data in all units accessible, and stores data proximate to the location where it is most frequently used. Distributed DBMSs should help resolve the islands of information problem. Databases are sometimes regarded, as electronic islands that are distinct and generally inaccessible places, like remote islands. This may be a result of geographical separation, inpatible puter architectures, inpatible munication protocols, and so on. Integrating the databases into a logical whole may prevent this way of thinking. 2． Concepts To start the discussion of distributed DBMSs, we first give a definition of a distributed database. Distributed database: a logically interrelated collection of shared data physically distributed over a puter work. Following on from this we have the definition of distributed DBMS. Distributed DBMS: the software system that permits the management of the distributed database and makes the distribution transparent to users. A distributed database management system consists of a single logical database that is split into a number of fragments. Each fragment is stored on one or more puters under the control of a separate DBMS, with the puters connected by a muni
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