Repository & UoW — Notes

Sizing

• One repository per aggregate root, period.
• Repository methods follow named-query convention (findActiveByCustomer).
• Pagination: cursor or page object as parameter, not exposed ORM type.

Concurrency

• Repository updates should respect aggregate version (@Version in JPA, xmin in Postgres).
• UoW commit catches version-conflict exceptions for retry by caller.

Caching

• Read-through cache in the repository implementation (transparent to use cases).
• Invalidate on save / delete.

Testing

• Use cases test against InMemoryOrderRepo — fast, deterministic.
• Adapter test suite runs the same contract against the real DB.

Refs

• Eric Evans: Domain-Driven Design — chapter on repositories.
• Martin Fowler: Patterns of Enterprise Application Architecture — Repository, Unit of Work, Data Mapper.
• Vaughn Vernon: Implementing DDD.
• "Architecture Patterns with Python" — Cosmic Python.