How Procedural Replication Works

Procedural replication executes your procedure call in the local database and queues a call to the procedure in all other master databases in the replication group, using whatever parameters you pass. This mechanism requires a “wrapper” procedure that calls the procedure that locally does the queueing. It also requires that the procedure be registered as a replicated object in all databases in the replication group.

As an example, suppose that we have a package procedure USER_ADMIN.CREATE_USER and a replicated wrapper package DEFER_USER_ADMIN. A call to the wrapper package results in the following chain of events:

  1. Call to DEFER_USER_ADMIN.CREATE_USER('SCOTT', ‘TIGER').

  2. DEFER_USER_ADMIN calls USER_ADMIN.CREATE_USER('SCOTT', ‘TIGER').

  3. Procedure USER_ADMIN.CREATE_USER executes locally.

  4. DEFER_USER_ADMIN builds a remote call to USER_ADMIN.CREATE_USER in other master databases in the same replication group. The remote call is placed in the deferred transaction queue.

  5. Procedure USER_ADMIN.CREATE_USER executes at remote databases.

Figure 14.1 depicts these events.

How procedural replication works

Figure 14-1. How procedural replication works

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