An important requirement while considering data consistency in masking, is maintaining empty cells as empty after masking. The flag KN (Keep Null) is used to achieve this. Check the KN checkbox along with any other Data consistency option to retain the empty cells after masking. The cells containing null values are kept null even after masking is done just to ensure the data remains realistic and can be used for further analysis.
This flag is externally available in RDBMS and RDS. For all other source systems Keep Null is managed automatically by PK Protect.
E.g., With reference to below image, the table displays the contacts and email addresses of employees in the database before masking is applied. If you look closely, there are few records in both the phone and email_add columns for which the data is NULL. To ensure that, even after masking is applied the data remains intact, you can check the KN flag for this.
When masking is applied with KN option, the null values in both phone and email_add remains intact across all the tables.
In the below image, the phone and email_ad details for emp_cd ‘110’ remains null even after applying masking. Similarly, if you would look closely, the phone numbers for emp_cd ‘103,106,108’ and email addresses for emp_cd ‘102,104,105,107,109’ are still marked NULL after masking is done.