Data redaction key concepts v17

The EDB Postgres Advanced Server Data redaction feature limits sensitive data exposure by dynamically changing data as it's displayed for certain users.

For example, a social security number (SSN) is stored as 021-23-9567. Privileged users can see the full SSN, while other users see only the last four digits: xxx-xx-9567.

You implement data redaction by defining a function for each field to which to apply redaction. The function returns the value to display to the users subject to the data redaction.

For example, for the SSN field, the redaction function returns xxx-xx-9567 for an input SSN of 021-23-9567.

For a salary field, a redaction function always returns $0.00, regardless of the input salary value.

These functions are then incorporated into a redaction policy by using the CREATE REDACTION POLICY command. In addition to other options, this command specifies:

• The table on which the policy applies
• The table columns affected by the specified redaction functions
• Expressions to determine the affect session users

The edb_data_redaction parameter in the postgresql.conf file then determines whether to apply data redaction.

By default, the parameter is enabled, so the redaction policy is in effect. The following occurs:

• Superusers and the table owner bypass data redaction and see the original data.
• All other users have the redaction policy applied and see the reformatted data.

If the parameter is disabled by having it set to FALSE during the session, then the following occurs:

• Superusers and the table owner bypass data redaction and see the original data.
• All other users get an error.

You can change a redaction policy using the ALTER REDACTION POLICY command. Or, you can eliminate it using the DROP REDACTION POLICY command.