關于分布式數(shù)據(jù)庫系統(tǒng)的計算機英語
計算機真的是我們?nèi)祟悜摵軅ゴ蟮陌l(fā)明，它促進了我們的生活，小編今天就給大家整理了有關于計算機的英語，僅供參考
計算機英語
Distributed Database System
A decentralized system-known in the database world as a distributed system can be highly responsive to differences in data gathering, storage, and access. It can adjust to differences in user psychol-ogy-between, say, a multinational corporation's employees in individualistic Greece and in disciplined Japan. It can also adapt to the management styles of strong managers in different locations.
An organization that prefers homogeneity and top-down control will naturally choose a centralized database system. It may also prefer the hierarchical data model.
By contrast, an organization that prefers local improvisation and free wheeling may well choose distributed database system. It may also choose the network data model，which is well suited to searching and updating data in a distributed system.
Communication between distributed commutinies of computer is required for many reasons.At a national level, for example, computers located in different parts of the country use public communication services to exchange electronic messages(mail) and to transfer files of information from one computer to another: Similarly, at a local level within, say, a single building or establishment, distributed communities of computer-based workstations use local communication networks to access expensive shared resources-for example, printers, copiers, disks and tapes, etc.-that are also managed by computers.Clearly, as the range of computer-based products and associated public and local com-medication networks procreate, computer-to-computer communication will expand rapidly and ultimately dominate the field of distributed system.
Historically, computers were so expensive that most large organizations did all their data processing on a single, centralized machine. While very efficient for such tasks as payroll and generating accounting reports, the centralized approach was very useful to those who needed a quick response to a unique, local problem.
With today's inexpensive micros and minis, there is no reason why a branch office, the engineer-in department, or any other group needing computer support cannot have its own computer. By linking these remote machines to a centralized computer via communication lines, local activity can be monitored and coordinated. This approach is called distributed data processing.
分散式系統(tǒng)在數(shù)據(jù)庫領域中稱為分布式系統(tǒng)，這種系統(tǒng)能處理不同的數(shù)據(jù)采集、存儲和訪問方一式。它可以根據(jù)用戶的心理，例如可針對個性強的希臘雇員和守紀律的日本雇員之間的差異作出調(diào)整，它也可適應不同地方的各種管理人員的不同管理風格。
傾向于均質(zhì)的、從上向下管理的組織機構自然要選擇集中式數(shù)據(jù)庫系統(tǒng)，這種組織也樂于使用層次型數(shù)據(jù)模型。
相反，傾向于臨時配置和對數(shù)據(jù)庫循環(huán)訪問的組織機構必然要選擇分布式數(shù)據(jù)庫系統(tǒng)，這種組織也樂于選擇網(wǎng)絡型數(shù)據(jù)模型，因為這種模型根適合于分布式系統(tǒng)數(shù)據(jù)查找和修改。
分布式計算機系統(tǒng)間需要進行通信有許多原因，例如在一個國家內(nèi)，處于各地的計算機使用公共通信設施交換電子信息(郵件)，從一個計算機向另一個計算機傳送文件。同樣，在一個局部區(qū)域內(nèi)。例如在一個大樓或機關內(nèi)，分布式的計算機工作站間 使用局部通信網(wǎng)絡訪問昂貴的共享資源，例如打印機、復印機、 磁盤和磁帶等，這些設備也由計算機管理。很明顯，隨著基于計算機的產(chǎn)品和相應的公共及局部通信網(wǎng)絡的激增，計算機一計算機通信也將得到迅速的發(fā)展，最終將在分布式系統(tǒng)中占統(tǒng)治地位。
從歷史上看，計算機是如此昂貴，這使得許多的大型組織機 構在作他們的數(shù)據(jù)處理時都得用一臺計算機一一中央機。這種集中處理的方法，對一些如象工資 和財務報表等任務來說是非常有效的，然而對另一些任務，如象需要對單一的、局部的問題作出快速相應的任務，就不是那么有效了。
由于現(xiàn)在微機和小型機都很便宜，因此在科室、工程部門， 或者任問需要計算機支持工作的團體部可以擁有自己的計算機。用通訊線路線路把這些遠程機器與中央計算機相連接，局部的話動就可以被監(jiān)視和協(xié)調(diào)。這種方式稱之為分布式數(shù)據(jù)處理。
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