First, let me give a brief explanation of what column aggregation inheritance is and how it works. With column aggregation inheritance all classes share the same table, and all columns must exist in the parent. Doctrine is able to know which class each row in the database belongs to by automatically setting a "type" column so that Doctrine can cast the correct class when hydrating data from the database. Even if you query the top level column aggregation class, the collection will return instances of the class that each row belongs to.