Database Reference
In-Depth Information
Issues and Challenges Because of the variety of multimedia objects and the
potential size of individual objects, multimedia databases are faced with difficult
issues and challenges. Here are a few that call for serious consideration.
Modeling and design. Although all types of multimedia may be considered objects,
because of the variations, creating a satisfactory database model is difficult. Design
issues are also hard to address.
Storage. Even when you have to store a large number of rows in relational
database systems, each individual row is of manageable size. On the other
hand, multimedia database systems must store and manage individually large
objects. Most databases define multimedia objects as a data type called BLOB
(binary large object).
Storage of large objects requires good compression
techniques.
Selection and retrieval. Users must be able to retrieve multimedia objects by spec-
ifying selection conditions based on content and similarity. For example, pictures
and images that are very similar must be able to be construed as the same object
and retrieved.
Query type. Query formulation and execution are different from those in relational
database systems, in which they are based on query languages and indexes.
Video-on-demand. Provision of this service for users by dialing into a server is
gaining momentum. The server must be able to handle special types of real-time
constraints and synchronization of video delivery at server and client.
Applications Although no comprehensive commercial systems are yet available,
the following types of applications will greatly benefit from multimedia database
systems.
Real-time alert, control, and monitoring
Entertainment and travel
Marketing and advertising
Education and training
Knowledge management
Document storage and retrieval
Mobile Databases
Mobile computing has become pervasive in today's business environment. You see
users with handheld devices, portable laptops, and notebooks transmitting data to
databases held in remote sites. The FedEx employee, delivering a package at your
front door, updates the package-tracking database from his handheld device. The
cop who pulled you over on a highway verifies your driver's license against an a
central database. The inventory taker at a large warehouse inputs the on-hand quan-
tities into the main inventory database from his handheld computing system. There
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