Row-Level Security in PostgreSQL: Multi-Tenant Data Isolation for Your SaaS Without a Query Change

--- title : " Row-Level Security in PostgreSQL: Multi-Tenant Isolation Without Changing a Single Query" published : true description : " Implement PostgreSQL RLS with JWT tenant context, PgBouncer transaction-mode safety, and CI testing via pgTAP — with real benchmarks and the pitfalls nobody warns you about." tags : postgresql, security, architecture, kotlin canonical_url : https://blog.mvpfactory.co/row-level-security-postgresql-saas-tenant-isolation --- ## What We're Building Let me show you a pattern I use in every multi-tenant project: PostgreSQL Row-Level Security (RLS) that isolates tenant data at the database layer — so you never scatter `WHERE tenant_id = ?` across every query again. By the end of this tutorial, you'll have: - RLS policies enforcing tenant isolation on every SELECT, UPDATE, and DELETE - Transaction-scoped tenant context injected from JWTs in Kotlin - A pgTAP test suite proving isolation holds in CI ## Prerequisites - PostgreSQL 14+ (we'll use 16 features, but