Staging and Propagation Process

Although Propagation is always between two queues, a single queue may participate in multiple propagations. In other words, a single queue may send events to multiple queues and at the same time receive from many queues. However, only one Propagation configuration is allowed between a particular source and destination.  As seen in the example shown in Figure 2.2, Type (A) shows the propagation from Queue at DB1 to queues at DB2, DB3, and DB4. Type (B) shows the queue at DB1 sending events to queue at DB2 and vice-versa. Configuring two propagations as shown in Type (C) is not allowed.

Figure 2.2 - Propagation between the Queues

 

The Propagation process uses the database links to the destination database from the source database.  The Propagation process uses job processes and is scheduled to run continuously. Once a schedule is completed, it immediately begins the next schedule.

Propagation Rules

The Propagation process either propagates or discards events based on rules that are defined by the DBA.

For LCR events, each rule specifies the database objects and types of changes for which the rule evaluates to TRUE. These rules can be placed in a positive rule set for the propagation or a negative rule set for the propagation. Rules can be defined at table level, schema level, or database level. For Non-LCR events, DBAs can create their own rules.