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Software → Software Design

Aggregate

A consistency boundary that groups domain objects and is modified through a single aggregate root.

Motivation

An Aggregate defines which domain objects must remain consistent together during a business operation.

Mental model

Treat an aggregate as one transactional unit. External code references and modifies it through its aggregate root.

Common mistakes

Making aggregates so large that every change becomes one transaction.
Exposing internal entities directly.
Using aggregates only as persistence containers.