Creation of Propagation Process

The propagation of events uses the dbms_job package and internally makes use of the job queue processes (Jnnn). A single propagation job propagates all events that use a particular database link even if the database link is used by more than one propagation to propagate events to multiple destination queues.

When a propagation is created, a dbms_job schedule which has the following properties is created:

• The start time is sysdate(), which says that it is to start immediately.
   

• The duration is NULL, which means infinite.  The process keeps running until it is dropped.
   

• The next time is NULL, which means that propagation restarts as soon as it finishes its current duration.
   

• The latency is 3 seconds, which is the wait time between when a queue becomes empty and the propagation job is resubmitted.

To create the propagation, any of the following procedures can be used:

• dbms_streams_adm.add_table_propagation_rules
   

• dbms_streams_adm.add_subset_propagation_rules
   

• dbms_streams_adm.add_schema_propagation_rules
   

• dbms_streams_adm.add_global_propagation_rules
   

• dbms_propagation_adm.create_propagation

Each of the procedures in the dbms_streams_adm package creates propagation with the specified name if it does not already exist.  It creates either a positive or negative rule set for the propagation if the propagation does not have such a rule set.  It may also add Table, Schema, or Global rules to the rule set.