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3 Various Databases

In present day society, database technology is applied in various areas. In companies, databases are used in many systems, such as corporate accounting systems, inventory control systems, document management systems, and sales support systems. In this section, we will learn about the database technology used in these systems.

3 - 1 Distributed Database

Distributed database is a technology that handles databases distributed at multiple sites as if they were one database. Databases are, by nature, used for the purpose of consolidating data and managing it in an integrated manner. However, there are following problems concerning databases consolidated over a network: the fault of a database affects the entire system, the network becomes over crowded because of concentration of processes, and maintenance/management of the database becomes difficult. Therefore, the concept of distributed database was developed where databases are dispersed and constructed at multiple sites. In the distributed database, by using the RDA (Remote Database Access) system, users can use the database without becoming aware of which database they are accessing. (This is called transparency of distributed database.) However, just like usual distributed processing systems, it suffers from the problem that operations, such as security management, take a lot of effort. In addition, it is possible that data may duplicated. Therefore, there is a risk that consistency of data is lost. In the distributed database, these problems are resolved with the following techniques. · 1 question

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