When you check Journal target mapping for a mapping, all actions on the source table (inserts, updates, and deletes) produce inserts into the target table.
You define the target table and the column mapping so that meaningful values are inserted into the target table. For example, before values of a deleted row, or the time that an operation was performed. Multiple updates produce multiple inserts into the source table which could also cause violations of the primary key constraint. You must define the target table and the mapping to prevent this from occurring.
For detailed information on journal mapping, refer to the Advanced User Guide.
Note: Journaling is useful for audits because it can provide a complete historical record of changes made to a database.