Definition - What does Distributed Database mean?
A distributed database is a type of database configuration that consists of loosely-coupled repositories of data. In a traditional database config all storage devices are attached to the same server, often because they are in the same physical location. A distributed database works as a single database system, even though the database hardware is run by by many devices in different locations.
Techopedia explains Distributed Database
The big issue with distributed databases is how to keep them current and in sync. In other words, how does replication get carried out, and how does referential integrity get maintained? A master/slave relationship is a big part of this. To simplify, a database is selected as the master, which is used during the replication process for other databases, which are designated slaves. During replication, specialized software is used to scan and check each database for inconsistencies and changes, which, once found, are replicated so that all databases look the same. This process can be complex and time-consuming as the database grows in number and size.