This is necessary to isolate the relational layer from the object layer, but this convenience comes at the cost of performance.

这对于将关系层与对象层分离是必需的，但这种便利是以牺牲性能为代价获得的。

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Base class for attributes that define how properties of types in the object layer are mapped to the properties of entity types or complex types in the conceptual model.

特性的基类，这些特性定义如何将对象层中的类型映射到概念模型中的实体类型和复杂类型。

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When the object layer is generated by the Entity Data Model tools, complex objects are instantiated when the complex type property is accessed, and not when the parent object is instantiated.

若对象层是由实体数据模型工具生成的，则复杂对象将在访问复杂类型属性而不是实例化父对象时进行实例化。

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The filament is designed to harden as it dries, so an object can be created layer by layer.

ECONOMIST: A new way to build complicated materials, micron by micron

Some experts have commented that Angel Ambush was not 'real' augmented reality at all, because the virtual angel was just a layer of video manipulated by a human operator, rather than an independent 3D object.

BBC: Augmented reality goes beyond gimmicks for business