A typical distributed database implementation involves corporate headquarters servers that
replicate data to departmental servers in various locations. Each database supports local client
applications and also has the ability to communicate with other databases in the network. This
architecture is shown in Figure 17-1.
Oracle Net allows this architecture to become reality. Run on all the servers involved, Oracle
Net allows database requests made from one database (or application) to be passed to another
database on a separate server. With this functionality, you can communicate with all the databases
that are accessible via your network. You can then create synonyms that give applications true
network transparency; the user who submits a query will not know the location of the data that
is used to resolve it.
You can configure Oracle to support multimaster replication (in which all databases involved
own the data and can serve as the source for data propagation) or single-master replication (in
which only one database owns the data). When designing a replication configuration, you should
try to restrict the ownership of data as much as possible. As the number of sources for propagation
increases, the potential for errors to occur increases, as does the potential administration workload.
In the following sections, you will see examples of the different replication capabilities available,
followed by management techniques.
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