Instantiation is the process of copying source objects to the target, to be able to start replication seamlessly with uninterrupted source database operations, complete data integrity, and error-free processing at the target database.

If an Extract process captures changes from the source database, you must instantiate the corresponding database objects at the target database before replication can begin. The target database must contain a copy of the source database objects to apply changes correctly, and both source and target objects must be consistent at a specific point in time. This point of consistency may be in the past. As long as the Extract was created beforehand, replication can start by capturing changes from older transaction logs (archive log files) and catching up with the backlog. The Replicat process will then begin applying changes from the exact moment when the source and target objects were consisten. However, changes earlier than that Instantiation time (Instantiation SCN) will be ignored, changes from that time and later will be applied.

In many cases, replication involves creating an exact copy of the source objects on the target side. However, there are scenarios where replication includes data modifications or transformations. In such cases, the target objects must be adjusted to accommodate these replication requirements.