"Object DBMSs add database functionality to object programming
languages. They bring much more than persistent storage of
programming language objects. Object DBMSs extend the semantics of
the C++, Smalltalk and Java object programming languages to provide
full-featured database programming capability, while retaining
native language compatibility. A major benefit of this approach is
the unification of the application and database development into a
seamless data model and language environment. As a result,
applications require less code, use more natural data modeling, and
code bases are easier to maintain. Object developers can write
complete database applications with a modest amount of additional
effort
In contrast to a relational DBMS where a complex data
structure must be flattened out to fit into tables or joined
together from those tables to form the in-memory structure, object
DBMSs have no performance overhead to store or retrieve a web or
hierarchy of interrelated objects. This one-to-one mapping of
object programming language objects to database objects has two
benefits over other storage approaches: it provides higher
performance management of objects, and it enables better management
of the complex interrelationships between objects. This makes
object DBMSs better suited to support applications such as
financial portfolio risk analysis systems, telecommunications
service applications, world wide web document structures, design
and manufacturing systems, and hospital patient record systems,
which have complex relationships between data."
(ODMG)