multitenancy

Multitenancy is a software architecture in which a single instance of a software application serves multiple tenants. A tenant is a group of users who share common access with specific data, configuration, and usage policies. The platform provides logical data isolation and customizations per tenant, while computing resources, instances, and maintenance are shared to improve efficiency. This model is common in software-as-a-service (SaaS) offerings, where providers can serve many customers from one codebase and infrastructure.

Implementation can be achieved through different tenancy patterns. In a database-per-tenant pattern, each tenant has its own database; in a schema-per-tenant model, a shared database contains separate schemas for tenants; in a shared-schema model, all tenants share tables with row-level isolation and tenant identifiers. Resource sharing extends to compute and storage, with service-level agreements that enforce performance isolation via throttling, quotas, or orchestration. Containers, virtualization, and orchestration platforms are often used to deploy and scale the same application instance.

Key advantages include reduced operational costs, easier maintenance, fast onboarding, and scalable growth. Challenges involve ensuring data isolation and security, performance isolation under noisy neighbors, upgrade management, customization support, and regulatory compliance. Proper tenant-aware design, auditing, and metering are essential for governance and chargeback or showback.

Common domains include SaaS products such as customer relationship management, email, collaboration tools, and analytics platforms. Multitenancy contrasts with single-tenant deployments, where each customer runs a separate instance. The choice of tenancy model depends on factors such as data isolation requirements, regulatory constraints, and expected scale.