Multi-tenant architecture enables SaaS platforms to serve multiple customers from shared infrastructure, dramatically improving operational efficiency. However, poorly designed multi-tenancy creates security vulnerabilities, performance issues, and data leakage risks. European SaaS companies must carefully architect tenant isolation while maintaining the cost benefits of resource sharing.
Tenancy Models
Three main multi-tenancy approaches exist with different isolation levels. Shared database with discriminator columns offers maximum efficiency but requires careful query filtering. Database-per-tenant improves isolation and enables tenant-specific customization. Infrastructure-per-tenant provides complete isolation but increases operational complexity. Hybrid approaches balance these factors for different customer tiers.
- Implement row-level security to prevent cross-tenant data access in shared schemas
- Use connection pooling per-tenant to limit resource consumption by individual tenants
- Design database schemas supporting both shared and isolated tenancy models
- Implement tenant context propagation across all application layers
- Build tenant-aware caching that maintains isolation while enabling efficiency
Performance Isolation
Resource contention between tenants creates unpredictable performance. Rate limiting prevents individual tenants from monopolizing shared resources. Quality of service tiers allocate resources proportionally to subscription levels. Circuit breakers prevent cascading failures when one tenant experiences issues. Monitoring per-tenant resource usage identifies problematic tenants requiring intervention.
Data Residency and Compliance
European SaaS platforms face data residency requirements that complicate multi-tenancy. Some tenants may require data storage in specific countries or regions. Architecture must support routing tenant data to appropriate geographic locations while maintaining application functionality. Compliance documentation should clearly explain data storage practices and tenant isolation mechanisms.