Advanced Access Control Mechanisms

Modern databases provide sophisticated access control mechanisms beyond basic table-level permissions. Row-level security (RLS) enables fine-grained access control where different users see different subsets of data based on security policies. This feature proves invaluable for multi-tenant applications, compliance requirements, and data isolation needs. Virtual Private Database (VPD) in Oracle and Row Level Security in PostgreSQL exemplify these capabilities.

Column-level encryption combined with key management provides cryptographic access control. Users without appropriate keys cannot decrypt sensitive columns even with database access. This approach protects against insider threats and provides defense-in-depth for highly sensitive data. However, encrypted columns cannot be indexed traditionally, requiring careful design to maintain query performance.

Dynamic data masking presents another access control layer, showing masked data to unauthorized users while revealing actual values to authorized ones. Credit card numbers might appear as "XXXX-XXXX-XXXX-1234" to support staff while showing full numbers to payment processors. This technique reduces data exposure without requiring application changes, though it should complement, not replace, proper access controls.