About Parallel Replicat

Parallel Replicat is another variant of Replicat that applies transactions in parallel to improve performance.

It takes into account dependencies between transactions, similar to Integrated Replicat. The dependency computation, parallelism of the mapping and apply is performed outside the database so can be off-loaded to another server. The transaction integrity is maintained in this process. In addition, parallel Replicat supports the parallel apply of large transactions by splitting a large transaction into chunks and applying them in parallel.

Note:

For best performance for an OLTP workload, parallel Replicat in non-integrated mode is recommended.

Only Oracle database supports parallel Replicat and integrated parallel Replicat. However, parallel Replicat supports all databases when using the non-integrated option.

To use parallel Replicat, you need to ensure that you have the following values, which are also the default values:

Metadata in the trail (which means you can't use parallel Replicat if your trails are formatted below 12.1.
Scheduling columns in the trail file.
UPDATERCORDFORMAT COMPACT parameter.

With integrated parallel Replicat, the Replicat sends the LCRs to the inbound server, which applies the data to the target database, and in regular parallel Replicat, Oracle GoldenGate applies the LCR as a SQL statement directly to the database, similar to how the other non-integrated Replicats work.

The components of parallel Replicat are:

Mappers operate in parallel to read the trail, map trail records, convert the mapped records to the Integrated Replicat LCR format, and send the LCRs to the Merger for further processing. While one Mapper maps one set of transactions, the next Mapper maps the next set of transactions. The the trail information is split and the trail file is untouched because it orders trail information in order.
Master processes have two threads, Collater and Scheduler. The Collater receives mapped transactions from the Mappers and puts them back into trail order for dependency calculation. The Scheduler calculates dependencies between transactions, groups transactions into independent batches, and sends the batches to the Appliers to be applied to the target database.
Appliers reorder records within a batch for array execution. It applies the batch to the target database and performs error handling. It also tracks applied transactions in checkpoint tables.

Note:

Parallel Replicat requires that any foreign key columns are indexed.