rls-reference

Overview

Postgres Row-Level Security (RLS) lets the database itself enforce per-tenant row visibility, independent of the application code. It is the canonical defence-in-depth layer for pool / horizontally-partitioned tenancy models - even if the application forgets to add a WHERE tenant_id = ? filter, the database refuses to return another tenant's rows.

Per postgresql.org/docs/current/ddl-rowsecurity.html, RLS "restricts which rows users can access based on per-user policies." Unlike standard SQL GRANT / REVOKE privileges which act on whole tables, RLS controls row visibility and modification per role.