Database-Enforced Isolation: PostgreSQL's Answer to Multi-Tenant Security Failures

Multi-tenant SaaS applications traditionally enforce tenant isolation in application code, but this approach consistently fails in production through overlooked authorization checks, code refactoring mistakes, and privilege escalation vulnerabilities. PostgreSQL Row-Level Security (RLS) moves enforcement to the database layer, making it cryptographically impossible for unauthorized code to access restricted rows regardless of implementation flaws. This shift represents a fundamental best practice evolution for protecting sensitive multi-tenant data at scale.