In Oracle About Data Replication and Integration:
 As organizations expand, it becomes increasingly important for them to be able to
share information among multiple databases and applications. Data replication and
integration enables you to access information when and where you need it in a
distributed environment. Oracle Database provides secure and standard mechanisms
that enable communication between databases, applications, and users. These
mechanisms include queues, data replication, messaging, and distributed access in
both homogeneous and heterogeneous environments.
This guide describes using distributed SQL, replication, and message queuing. You
can make efficient use of your computing resources by using these features to
complete the following types of tasks:
■ Replicate data between databases
■ Provide easy access to data in distributed databases
■ Exchange data between Oracle databases and non-Oracle databases
■ Enable communication between applications
■ Exchange information with customers, partners, and suppliers
■ Provide event notification and workflow

Oracle Database provides the following types of data replication and integration
solutions to address your specific requirements:
■ Consolidation: All data is moved into a single database and managed from a
central location. Oracle Real Application Clusters (Oracle RAC), Grid computing,
and Virtual Private Database (VPD) can help you consolidate information into a
single database that is highly available, scalable, and secure.
■ Federation: Data appears to be integrated in a single virtual database, while
actually remaining in its current distributed locations. Distributed queries,
distributed SQL, and Oracle Database Gateway can help you create a federated
database.
■ Sharing: Multiple copies of same information are maintained in multiple
databases and application data stores. Data replication and messaging can help
you share information at multiple databases.