In a coordinated Replicat configuration, barrier transactions such as updates to the primary key cause an increased number of commits to the database, and they interrupt the benefit of the GROUPTRANSOPS feature of Replicat. When there is a high number of barrier transactions in the overall workload of the coordinated Replicat, using a high number of threads can actually degrade Replicat performance.

To maintain high performance when large numbers of barrier transactions are expected, you can do the following:

• Reduce the number of active threads in the group. This reduces the overall number of commits that Replicat performs.

• Move the tables that account for the majority of the barrier transactions, and any tables with which they have dependencies, to a separate coordinated Replicat group that has a small number of threads. Keep the tables that have minimal barrier transactions in the original Replicat group with the higher number of threads, so that parallel performance is maintained without interruption by barrier transactions.

• (Oracle RAC) In a new Replicat configuration, you can increase the PCTFREE attribute of the Replicat checkpoint table. However, this must be done before Replicat is started for the first time. The recommended value of PCTFREE is 90.