SaaS applications serve multiple customers (tenants) from the same codebase. The challenge is keeping data isolated while sharing infrastructure efficiently.
Multi-Tenancy Strategies
Shared Database, Shared Schema:
- All tenants in same tables
- Tenant ID column for filtering
- Simplest, least isolated
- Best for: Most SaaS apps
Shared Database, Separate Schemas:
- Each tenant has own schema
- Better isolation
- More complex migrations
- Best for: Regulated industries
Separate Databases:
- Each tenant has own database
- Complete isolation
- Highest overhead
- Best for: Enterprise customers
Shared Schema Implementation
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Tenant Context
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Tenant-Scoped Queries
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Row-Level Security (PostgreSQL)
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Tenant-Aware Caching
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Tenant Provisioning
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Tenant Limits
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Best Practices
Data Isolation:
✓ Always filter by tenant ID
✓ Use database-level RLS when possible
✓ Audit cross-tenant access
✓ Test isolation thoroughly
Performance:
✓ Index tenant_id columns
✓ Partition large tables by tenant
✓ Implement tenant-aware caching
✓ Monitor per-tenant usage
Operations:
✓ Automate tenant provisioning
✓ Plan for tenant deletion
✓ Support data export
✓ Implement tenant backups
Conclusion
Multi-tenancy requires careful attention to data isolation and performance. Start with shared schema for simplicity, use row-level security for protection, and implement tenant context throughout your application.
Always test that one tenant cannot access another tenant's data.