Storing and maintaining semistructured data efficiently in an object-relational database

We propose to use object-relational database management systems to store and manage semi-structured data. ORA-SS (Object-Relationship-Attribute model for Semi-Structured data) (Dobbie et al., 2000) is used as the data model. It not only reflects the nested structure of semi-structured data, but also distinguishes between object classes and relationship types, and between attributes of object classes and attributes of relationship types. ORA-SS can specify the degree of n-ary relationship types and indicate if an attribute is an attribute of a relationship type or an attribute of an object class. Existing semi-structured data models cannot specify such information. We use this information to translate XML Schemas/DTD to ORA-SS schemas, then to object-relational databases correctly and without avoidable redundancy. The existing techniques have a lot of redundancy in storage and introduce node IDs of the tree instance which are not needed in our approach.