Term Paper on Distributed Databases
INTRODUCTION
In today’s world of universal dependence on information systems, all sorts of people need access to companies’ databases. In addition to a company’s own employees, these include the company’s customers, potential customers, suppliers, and vendors of all types. It is possible for a company to have all of its databases concentrated at one mainframe computer site with worldwide access to this site provided by telecommunications networks, including the Internet. Although the management of such a centralized system and its databases can be controlled in a well-contained manner and this can be advantageous, it poses some problems as well. For example, if the single site goes down, then everyone is blocked from accessing the databases until the site comes back up again. Also the communications costs from the many far-flung PCs and terminals to the central site can be expensive. One solution to such problems, and an alternative design to the centralized database concept, is known as distributed database.
The idea is that instead of having one, centralized database, we are going to spread the data out among the cities on the distributed network, each of which has its own computer and data storage facilities. All of this distributed data is still considered to be a single logical database. When a person or process anywhere on the distributed network queries the database, it is not necessary to know where on the network the data being sought is located. The user just issues the query, and the result is returned. This feature is known as location transparency. This can become rather complex very quickly, and it must be managed by sophisticated software known as a distributed database management system or distributed DBMS.
A distributed database is a Data Collection which satisfies the following assumptions: resides on more than one machine with computational power; machines are connected by a communication network; it benefits of a distributed database
In today’s world of universal dependence on information systems, all sorts of people need access to companies’ databases. In addition to a company’s own employees, these include the company’s customers, potential customers, suppliers, and vendors of all types. It is possible for a company to have all of its databases concentrated at one mainframe computer site with worldwide access to this site provided by telecommunications networks, including the Internet. Although the management of such a centralized system and its databases can be controlled in a well-contained manner and this can be advantageous, it poses some problems as well. For example, if the single site goes down, then everyone is blocked from accessing the databases until the site comes back up again. Also the communications costs from the many far-flung PCs and terminals to the central site can be expensive. One solution to such problems, and an alternative design to the centralized database concept, is known as distributed database.
The idea is that instead of having one, centralized database, we are going to spread the data out among the cities on the distributed network, each of which has its own computer and data storage facilities. All of this distributed data is still considered to be a single logical database. When a person or process anywhere on the distributed network queries the database, it is not necessary to know where on the network the data being sought is located. The user just issues the query, and the result is returned. This feature is known as location transparency. This can become rather complex very quickly, and it must be managed by sophisticated software known as a distributed database management system or distributed DBMS.
A distributed database is a Data Collection which satisfies the following assumptions: resides on more than one machine with computational power; machines are connected by a communication network; it benefits of a distributed database