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Multi-Tenant Isolation in PostgreSQL: Lessons from Building ETLab+

Architecting Row-Level Security (RLS) policies in PostgreSQL to enforce strict data isolation across college lab departments.

PostgreSQLDatabaseSecurityFull StackRow-Level Security
# Context & Architecture Challenge In building **ETLab+**, multiple academic departments (CS, EC, EEE) required access to shared laboratory facilities while enforcing strict row-level data segregation. ## PostgreSQL Row-Level Security Policy ```sql ALTER TABLE lab_reservations ENABLE ROW LEVEL SECURITY; CREATE POLICY tenant_isolation_policy ON lab_reservations USING (department_id = current_setting('app.current_department_id')); ``` ## Performance & Query Execution Results By indexing `(department_id, reservation_date)` compound keys, query latency remained under 4ms across 10,000+ attendance records. > **Key Lesson**: Enforcing security policies at the database engine level eliminates application-tier permission leaks and concurrency race conditions.