Designing Multi-Tenant Systems That Don't Break at Growth
October 22, 2025 • 6 min read
Every SaaS product eventually faces the same question — how to manage multiple customers (tenants) efficiently
without compromising isolation, scalability, or cost.
There are three dominant patterns:
1. Shared Database, Shared Schema — simplest to manage but hardest to isolate.
2. Shared Database, Isolated Schemas — moderate isolation with good scaling trade-offs.
3. Database per Tenant — best for enterprise-grade isolation and performance, but more complex operationally.
A robust architecture often starts hybrid — small tenants share DBs, large ones get isolated.
This “tiered tenancy model” keeps infra costs predictable while enabling growth without re-architecture.
Growth-friendly SaaS systems are designed with migration in mind — making it easy to move a tenant between
database tiers seamlessly. Build that in early, and scale will never force a rewrite.