TRENDS IN DATABASE TECHNOLOGY - Database Design and Development: An Essential Guide for IT Professionals - page 636

It appeared that organizations had to make the choice only between relational
and object-oriented systems. There was no middle path. This has been changing in
recent years. What seem to be needed are database systems that would allow rep-
resentation of complex data types, user-defined functions to assist in processing, and
user-defined operators to carry out complicated functions. SQL-92 is inadequate in
this regard; so are pure object-oriented database systems.
An object-relational database system presents a viable solution for handling
complex data types. It combines the capabilities of object technology with the
features of data integrity, reliability, recovery, and security found in relational
technology.
The Driving Forces
Users are moving to object-relational database management systems (ORDBMSs)
not so much for object orientation. The need for new data types such as HTML
pages, huge unstructured documents, audio, video—all of this within the relational
infrastructure—is what drives the transition to ORDBMS.
Michael Stonebraker, a database expert and founder of the ORDBMS vendor
Illustra, describes the characteristics of an ORDBMS. In his fundamental book,
Object-Relational DBMSs , Stonebraker refers to a typical application at the State
of California Department of Water Resources (DWR) that manages the waterways,
canals, and water projects in that state. DWR maintains a library of nearly half
a million pictures. DWR employees access this library several times a day. An
employee would need to request for a picture by content with a query such as: show
me Lake Cachuma (a Santa Barbara county reservoir) with a low water level.
Despite an index system of captions and keywords, retrieval of the right picture
within a reasonable time is virtually impossible. Information requirements such as
this need a database system that would allow representation of complex data types
and mechanisms to query and manipulate these data types.
When you group the various factors that have given rise to the object-relational
system, you will note that two major forces propel ORDBMS: computerization of
new types of applications and sophistication of business data processing applica-
tions. Let us consider these two driving forces.
New Types of Applications What we notice is an ever-growing number of appli-
cations in new areas. New types of applications range in variety from satellite
imaging, weather forecasting, flood control, engineering design, and bio-engineer-
ing to spatial, geographic, and temporal systems. In particular, new types of multi-
media applications keep increasing in the following areas.
Web applications Developers are loading up the World Wide Web with complex
data at an amazing rate. Using the Web as a transport vehicle, Web applications
require the means to run complex queries on complex data types such as multi-
media objects.
Digital images Over the next decade, X-ray, ultrasound, and other such systems
are expected to store enormous amounts of data on digital storage devices. Useful