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 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.
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