About N-Way Replication Environments

An n-way replication environment is one in which each database communicates directly with each other database in the environment. The changes made to replicated database objects at one database are captured and sent directly to each of the other databases in the environment, where they are applied.

An n-way replication environment typically has the following basic components:

• Each database has one or more capture processes or synchronous captures to capture changes to the replicated database objects.

• Each database has propagations that send the captured changes to each of the other databases.

• Each database has apply processes that apply changes from each of the other databases. A different apply process must apply changes from each source database.

• For the best performance, each capture process and apply process has its own queue.

Figure: N-Way Replication Environment shows an n-way replication environment.

You can configure an n-way replication environment by using the following Oracle-supplied packages:

• DBMS_STREAMS_ADM can be used to perform most of the configuration actions, including setting up queues, creating capture processes or synchronous captures, creating propagations, creating apply processes, and configuring rules and rule sets for the replication environment.

• DBMS_CAPTURE_ADM can be used to start any capture processes you configured in the replication environment.

• DBMS_APPLY_ADM can be used to configure apply processes, configure conflict resolution, and start apply processes, as well as other configuration tasks.

See "When to Replicate Data with Oracle Streams" for information about when n-way replication is useful.

Typically, in an n-way replication environment, you should configure conflict resolution to keep the replicated database objects synchronized.

Configuring an n-way replication environment is beyond the scope of this guide. See Oracle Streams Extended Examples for a detailed example that configures an n-way replication environment.