SaaS Multi-Tenant Database Architecture: Row-Level Security vs Database-per-Tenant
Compare PostgreSQL row-level security and database-per-tenant designs across isolation, performance, operations, and cost.
Article Focus
SaaS ArchitecturePrimary Topic
10 min readReading Time
PracticalExecution Style
StructuredContext Flow
SaaS Multi-Tenant Database Architecture: Row-Level Security vs Database-per-Tenant
Tenant isolation is an architectural decision that affects security, migrations, support, and unit economics. PostgreSQL row-level security is usually the efficient default; separate databases can be worthwhile for strict isolation or bespoke compliance.
Row-level security schema
CREATE TABLE projects (id uuid, tenant_id uuid NOT NULL, name text);
ALTER TABLE projects ENABLE ROW LEVEL SECURITY;
CREATE POLICY tenant_isolation ON projects USING (tenant_id = current_setting('app.tenant_id')::uuid);Tradeoff table
| Dimension | RLS/shared database | Database per tenant |
|---|---|---|
| Cost | Lower at scale | Higher infrastructure overhead |
| Isolation | Policy-enforced | Physical boundary |
| Operations | Central migrations | Fleet management required |
| Performance | Efficient shared pools | Predictable noisy-neighbor control |
Recommendation
Start with RLS, automated tenant-context middleware, and tests that prove cross-tenant queries fail. Move high-compliance or very large tenants to isolated databases when measurable requirements justify the operational cost.