What is Multi-Tenant Database Architecture?
Multi-tenant database architecture is a pattern enabling multiple customers (tenants) to share database infrastructure while maintaining data isolation and security. This approach is fundamental to modern SaaS applications, offering significant cost savings and operational efficiency.
Key Benefit: Shared infrastructure reduces per-tenant costs by up to 70% while maintaining a single codebase and database to maintain.
Three Main Approaches to Multi-Tenancy
1. Shared Database, Shared Schema
All tenants share the same database and tables. A tenant identifier column distinguishes data ownership.
CREATE TABLE orders (
id BIGINT PRIMARY KEY,
tenant_id INT NOT NULL,
customer_id INT,
total DECIMAL(10,2),
INDEX idx_tenant (tenant_id)
);Pros: Lowest cost, simplest maintenance, efficient resource utilization
Cons: Highest risk of data leakage, complex queries, noisy neighbor issues
2. Shared Database, Separate Schemas
Each tenant has their own schema within a shared database, providing better isolation while sharing infrastructure.
-- Create schema per tenant
CREATE SCHEMA tenant_acme;
CREATE SCHEMA tenant_globex;
-- Each schema has identical tables
CREATE TABLE tenant_acme.orders (...);
CREATE TABLE tenant_globex.orders (...);Pros: Better isolation, easier backup/restore per tenant, simpler queries
Cons: Schema management overhead, limited scalability
3. Separate Databases per Tenant
Each tenant gets their own dedicated database, providing maximum isolation and customization flexibility.
Pros: Maximum isolation, easy customization, simplified compliance
Cons: Highest cost, complex management, resource inefficiency
Multi-Tenant Architecture Comparison
| Approach | Isolation | Cost | Complexity | Best For |
|---|---|---|---|---|
| Shared DB/Schema | Low | Lowest | Low | Startups, B2C |
| Shared DB/Separate Schema | Medium | Medium | Medium | Growing SaaS |
| Separate Databases | High | Highest | High | Enterprise, Regulated |
Security and Data Isolation
Regardless of the approach chosen, implementing proper security measures is critical:
- Row-Level Security (RLS): Enforce data access at the database level
- Application-Level Filtering: Always include tenant context in queries
- Connection Pooling: Isolate connection pools per tenant for high-security needs
- Encryption: Implement tenant-specific encryption keys for sensitive data
Key Facts and Statistics
- 70% cost reduction possible through multi-tenancy
- 85% of SaaS applications use multi-tenant architecture
- 99.9% uptime achievable with proper implementation
Conclusion
Choosing the right multi-tenant architecture depends on your specific requirements for isolation, compliance, cost, and operational complexity. Start with a shared approach for cost efficiency, and evolve toward more isolated architectures as your business and customer requirements grow.