In a true sense the broadcasting (or data distribution) replication involves sending data changes from one source to multiple targets, using the same source Shareplex instance. In this kind of setup, the source and target use the same port number to communicate.
There is an alternate way by which replication can be configured so that the source server has multiple instances of Shareplex, each replicating to a different target server using different port. For example, one can create a source instance on port 2100 to replicate to one target that is also configured to listen on port 2100, create a second source instance on port 2200 to replicate to the second target that listens on port 2200, and so on.
This solution delves on the preferred way out of the two to achieve this.
It is preferred to use the same source Shareplex instance to configure a broadcasting replication. Here are some of the advantages:
A.It is easier to configure and maintain. The following are some common maintenance tasks performed on source and the ease of former approach is self evident, as one only has to perform the tasks on one source Shareplex instance:
1.Making changes to config file to include or exclude tables.
2.Tuning of Shareplex processes.
3.Monitoring of Shareplex processes.
4.Upgrade of Shareplex, operating system or Oracle.
B.It is less resource intensive on the source server. Redundancy is avoided for the following:
1.Number of Shareplex processes: There is only one Capture, Export, etc, that serves all the targets.
2.Disk space usage by Shareplex queues: There is only one set of Capture and Export queues.
3.Disk and database resource contention: There is only one Capture process reading the archive logs. There is only one set of Capture and Read processes that make connection to the database.
There are situations where it may be appropriate to have separate source Shareplex instances replicate to different target Shareplex instances. One such situation is where the tables replicated to various targets are different. In this scenario it will be ok to have separate Shareplex instances configured to replicate to different targets as in a certain sense they are different replication entities. Though it is still possible to use the same source Shareplex instance replicate different tables to different targets.