The present invention provides a method and mechanism to store and manage self-descriptive heterogeneous data in a database system. In one embodiment, a generic datatype is defined which encapsulate type descriptions along with the actual data itself. Another generic datatype is defined to encapsulate structural information for new datatypes. By using these generic datatypes to encapsulate heterogeneous data, the database system can be made aware of the exact structure and format of the heterogeneous data. This permits users and the database system to store, manage, and access the heterogeneous data like known datatypes in the system. Other objects, advantages, and features of the invention are described in the Drawings, Claims, and Detailed Description.