Replication Server includes high volume adaptive replication (HVAR), which provides better performance compared to the current continuous replication mode when replicating into databases with identical database schema.
In continuous replication mode, Replication Server sends each logged change to the replicate database according to the log order in primary database. HVAR achieves better performance by using:
Compilation – rearranges replicate data by each table, and each insert, update, and delete operation, and compiling the operations into net-row operations.
Bulk apply – applies the net result of the compilation operations in bulk using the most efficient bulk interface for the net result. Replication Server uses an in-memory net-change database to store the changes, which it then applies to the replicate database.
Instead of sending every logged operation, compilation removes the intermediate insert, update, or delete operations in a group of operations and sends only the final compiled state of a replicated transaction. Depending on the transaction profile, this generally means that Replication Server sends a smaller number of commands to the replicate database to process.
HVAR groups as many compilable transactions as possible, compiles the transactions in the group into a net change, and then uses the bulk interface in the replicate database to apply the net changes to the replicate database.
As Replication Server compiles and combines a larger number of transactions into a group, bulk operation processing improves; therefore, replication throughput and performance also improves. You can adjust group sizes to control the amount of data that is grouped together for bulk apply.
HVAR is especially useful for creating online transaction processing (OLTP) archiving and reporting systems where the replicate databases have the same schemas as the primary databases.