Summary: Shared database, separate schemas or separate databases? Compare multi-tenant architectures for SaaS products.
Multi-tenancy lets one application serve many customers while keeping their data separate. There are three common models.
| Model | Description | Pros | Cons |
|---|---|---|---|
| Shared database, shared schema | All tenants in the same tables with a tenant ID | Simple, cost-efficient | Requires strict access control |
| Shared database, separate schemas | Each tenant has its own schema | Better isolation | More complex migrations |
| Separate databases | Each tenant has its own database | Strongest isolation, per-tenant scaling | Higher cost and operational effort |
How to choose
- Early-stage SaaS: shared schema with row-level security is usually best.
- Regulated industries or enterprise clients: separate databases may be required.
- Hybrid: most tenants share, large customers get dedicated databases.
Essentials regardless of model
- Tenant context enforced on every query
- Automated tests for data isolation
- Per-tenant backups and export
- Usage metering for billing
FAQs
Can I change models later?
Yes, but it's work. Design abstractions that make the tenant boundary explicit.
Does PostgreSQL help?
Yes, Row-Level Security policies add a strong safety net.
How do I handle custom domains per tenant?
Map domains to tenants at the routing layer and automate SSL.
