Whether you need to specify the base entity's key to query navigation property views.
This connection property is primarily used with limited OData APIs; it determines whether navigation properties can be retrieved from the base entity set. In OData, navigation properties link a base entity to a related entity or a collection of related entitites.
For more on navigation properties, see Data Model.
Working with Limited APIs
In OData, the $expand parameter is used to expand specified navigation properties when requesting data from a given entity set. In SQL, this makes it possible to execute a SELECT * to a navigation property view.
If $expand is not supported, a different request must be made to retrieve a navigation property, one that specifies the primary key of the base entity set. This API restriction is reflected in SQL: You will need to specify the base entity's primary key in the WHERE clause.
For example, consider two entities with a one-to-many relationship in the Northwind sample service, Categories and Products. In OData, the Products associated with a given Category could be represented as a navigation property on the base Category entity set. The adapter models the Products navigation property as a Categories_Products view.
If $expand is not supported, use a query like the following to this view:
SELECT * FROM Categories_Products WHERE (Categories_CategoryID = 1)