A method and apparatus for managing hierarchical relationships in a relational database system is provided. An “orderkey” data type, which is native within a relational database system, is disclosed. The orderkey type is designed to contain values that represent the position of an entity relative to the positions of other entities within a hierarchy. Such values represent hierarchical relationships between those entities. Values that are of the orderkey type have properties that allow hierarchy-oriented functions to be performed in an especially efficient manner. Database functions, which operate on and/or produce values that are of the orderkey type, are also disclosed. Such functions can be placed within SQL statements that a database server executes, for example. In response to executing SQL statements that contain such functions, the database server performs hierarchy-oriented operations in a highly efficient manner.