To facilitate application requests in a distributed database system, Oracle uses database links . A database link defines a one-way communication path from an Oracle database to another database. Database links are essentially transparent to the users of an Oracle distributed database system, because the name of a database link is the same as the global name of the database to which the link points. The next section explains how applications can reference remote schema objects in a distributed database and includes examples of how SQL statements use database links. Distributed Database Systems for more information.
Oracle forms object names using a hierarchical approach.
For example, within a single database, Oracle guarantees that each schema has a unique name, and that within a schema, each object has a unique name. As a result, a schema object's name is always unique within the database. Furthermore, Oracle can easily resolve application references to a schema object's local name. In a distributed database, a schema object such as a table is accessible to all applications in the system. Oracle simply extends the hierarchical naming model with global database names to effectively create global object names and resolve references to the schema objects in a distributed database system.