Database Reference
In-Depth Information
these objectives help you to develop an early appreciation for the field; they should
also provide useful insight into where the course is heading. As you will soon see, these
objectives are lofty, and it is by no means easy to achieve them all.
The primary objectives of a database system include the following:
•
Security and protection — prevention of unauthorized users;
protection from inter-process interference
•
Reliability — assurance of stable, predictable performance
•
Facilitation of multiple users
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Flexibility — the ability to obtain data and effect action via
various methods
•
Ease of data access and data change
•
Accuracy and consistency
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Clarity — standardization of data to avoid ambiguity
•
Ability to service unanticipated requests
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Protection of intellectual Investment
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Minimization of data proliferation — new application needs may be
met with existing data rather than creating new files and programs
•
Availability — data is available to users whenever it is required
Among the significant secondary objectives of a database system are the following:
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Physical data independence — storage hardware and storage
techniques are insulated from application programs
•
Logical data independence — data items can be added or
subtracted or the overall logical structure modified without
existing programs being affected
•
Control of redundancy
•
Integrity controls — range checks and other controls must
prevent invalid data from entering the system
•
Clear data definition — a data dictionary is usually kept
•
Suitably friendly user interface
•
Tunability — easy reorganizing the database to improve
performance without changing the application programs
•
Automatic reorganization of migration to improve performance
