Скачать или смотреть A Distributed Database Management System.

A Distributed Database Management System (DDBMS) is essentially a software system designed to manage a database spread across multiple computers or locations on a network. Imagine a giant database that's not confined to one server but rather scattered across different sites, yet appears as a single, unified database to users.

Distributed Database: The data itself is split and stored on various computers or servers across a network. This could be due to geographical reasons (data centers in different countries) or to handle massive amounts of information.
Management System: The DDBMS acts as the central control system. It ensures all these separate databases function as one, transparently handling data retrieval, storage, and updates. Users interact with the DDBMS as if they're accessing a single, local database.

There are several advantages to using a DDBMS:

Improved Availability and Reliability: If one site fails, the system can still function using data from other locations.
Scalability: As data needs grow, the DDBMS can easily incorporate additional servers to handle the increased load.
Improved Performance: Distributing data can improve retrieval speeds for geographically dispersed users.

However, DDBMS also comes with its own set of challenges:

Complexity: Managing a distributed system requires more intricate setup and maintenance compared to a centralized system.
Data Consistency: Ensuring all copies of data across different sites remain consistent requires additional mechanisms within the DDBMS.
Overall, DDBMS offers a powerful solution for managing large-scale databases or those requiring high availability and scalability.