Page 156 - DMGT505_MANAGEMENT_INFORMATION_SYSTEM

Unit 8: Databases and Data Warehouses

3. Easier database design, implementation, management & use Notes
4. Ad hoc querying (a query that is not predefined) capability through SQL
5. Powerful data management system.
The disadvantages, on the other hand, are:
1. Substantial hardware & system software overhead
2. Possibility of poor design & implementation

3. Potential “islands of information” problem.

8.3.2 Object-oriented Model

The object-oriented paradigm has been applied to database technology, creating a new
programming model known as object databases. These databases attempt to bring the database
world and the application programming world closer together, in particular by ensuring that the
database uses the same type system as the application program. This aims to avoid the overhead
(sometimes referred to as the impedance mismatch) of converting information between its
representation in the database (for example, as rows in tables) and its representation in the application
program (typically as objects). At the same time, object databases attempt to introduce the key
ideas of object programming, such as encapsulation and polymorphism, into the world of databases.
Figure 8.5: Object Oriented Model

A variety of these ways have been tried for storing objects in a database. Some products have
approached the problem from the application programming end, by making the objects
manipulated by the program persistent. This also typically requires the addition of some kind
of query language, since conventional programming languages do not have the ability to find
objects based on their information content. Others have attacked the problem from the database
end, by defining an object-oriented data model for the database, and defining a database
programming language that allows full programming capabilities as well as traditional query
facilities.
Object databases suffered because of a lack of standardization: Although standards were defined
by ODMG, they were never implemented well enough to ensure interoperability between
products. Nevertheless, object databases have been used successfully in many applications:
usually specialized applications such as engineering databases or molecular biology databases
rather than mainstream commercial data processing.

Notes Object database ideas were picked up by the relational vendors and influenced
extensions made to these products and indeed to the SQL language.

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