Ideally, every key value in the index is unique.

理想情况是，索引中的每个键值都是惟一的。

Compass configuration is based on key value Settings.

Compass的配置基于“键—值”的一一对应的设置。

Fourth, call the KeyManger to get the primary key value.

第四，调用KeyManger来获得主键值。

The key value indicates the type of relationship being asserted.

键值表明要声明的关系的类型。