We will include this Key as an attribute of AcmeMembership, mark it as a Primary Key, and specify the strategy the Google App Engine runtime will use to populate it automatically with unique values.

我们将会将该Key作为AcmeMembership的属性添加，并将其标记为一个主键，并指定Google App Engine运行时的策略，它将会自动填充上唯一的值。

youdao

An entity's primary key is the attribute or set of attributes that distinguish one instance of the entity from another.

实体的主键是使该实体的一个实例区别于其他实例的一个或一组属性。

youdao

Make a separate table for each set of related attributes, and give each table a primary key. Each field contains at most one value from its attribute domain.

为每个相关属性的集合创建一个单独的表，并为每个表指定一个主键。每列最多包含一个来自其属性域的值。

youdao