"Free database queries can actually breach the encapsulation of domain objects and AGGREGATES." #readingToday

A subset of persistent objects must be globally accessible through a search based on object attributes. Such access is needed for the roots of AGGREGATES that are not convenient to reach by traversal. They are usually ENTITIES, sometimes VALUE OBJECTS with complex internal structure, and sometimes enumerated VALUES. Providing access to other objects muddies important distinctions. Free database queries can actually breach the encapsulation of domain objects and AGGREGATES. Exposure of technical infrastructure and database access mechanisms complicates the client and obscures the MODEL-DRIVEN DESIGN.

Domain-Driven Design, Eric Evans