Definition

Federation refers to a setup where multiple autonomous databases or services coordinate to respond to queries, often by delegating parts of a query to different sources, but without a shared storage layer.

Core concept

Often used in multi-tenant SaaS: each tenant has its own DB, and a proxy layer (federation engine) routes queries to the correct shard. The data is not physically unified.

Use cases

SaaS scaling, horizontal sharding with independent nodes.

References

Typical concept in distributed DB, no specific source.