Defining delete row compare options
The delete process can compare rows in the source file and database and then delete only rows from the database that exactly match rows in the source file. Use this option to prevent losing updates to the data in the database since the archive or extract was performed.
This option is available for tables with a unique primary key only. Rows that do not match are discarded and noted in the control file. You can specify whether to include LOB data in the comparison.
Note that using this option might improve performance significantly. However, if you do not use this option, you will not receive any warnings (for example, a warning of a “not found” condition if a row in the source file does not exist in the DBMS).