What is Virtual Private Database in Oracle?

Virtual Private Database (VPD), a feature of Oracle Database 11g Enterprise Edition, was introduced in Oracle8i and is one of the most popular security features in the database. VPD is used when the standard object privileges and associated database roles are insufficient to meet application security requirements. VPD policies can be simple or complex depending on your security requirements. VPD can be used in combination with the "application context" feature to enforce sophisticated row and/or column level security requirements for privacy and regulatory compliance. A simple VPD example might restrict access to data during business hours and a more complex VPD example might read an application context during a login trigger and enforce row level security against the ORDERS table.