Database per Service

Each service owns its database and no other service reads or writes it directly.

data

Detailed Description

Data ownership is one of the strongest service boundaries. A service API becomes the only allowed access path.

This enables independent evolution but pushes cross-service read needs into composition, projections, or events.

UserService -> User DB
OrderService -> Order DB
PaymentService -> Payment DB
No cross-DB access

Pros

Loose coupling, independent schema changes

Cons

Cross-service queries become harder

Examples: Microservices data ownership best practice