Working with Object-relational Descriptors

The object-relational paradigm extends traditional relational databases with object-oriented functionality. Oracle, IBM DB2, Informix, and other DBMS databases allow users to store, access, and use complex data in more sophisticated ways.

The object-relational standard is an evolving standard mainly concerned with extending the database data structures and the SQL language (SQL 3).

The new features include:

Structures or Object-types can be defined and stored on the database
Collections/Arrays can be defined and stored on the database
Structures/Object-types can have system-generated ObjectIDs
Structures/Object-types can reference other structures through References or aggregation
SQL 3, an extension to the SQL language that supports querying and manipulating the new object-types

Coinciding with object-relational changes, most database vendors are also extending their server architectures to support features such as:

Embedded server-side Java VMs
Java stored procedures
CORBA, HTML and EJB support in the database

This section describes how the object-relational features affect TopLink descriptors and mappings.