Question

Although database systems have become the system of choice for new and reengineered systems, are there any situations where a traditional file based system might be chosen instead? Explain your answer with examples.

Answer 1

A traditional file-based system is chosen instead of database systems has a number of disadvantages.

Data redundancy

In an organization, files and applications are created by different programmers from various departments over long periods of time. This can lead to data redundancy, a situation that occurs in a database when a field needs to be updated in more than one table. This leads to several problems such as:

• Inconsistency in data format
• The same information being kept in several different files
• Data inconsistency, a situation where various copies of the same data are conflicting, wastes storage space and duplicates effort

Data isolation

Data isolation  is a property that determines when and how changes made by one operation become visible to other concurrent users and systems and this issue occurs in a concurrency situation. It is difficult for new applications to retrieve the appropriate data, which might be stored in various files.

Integrity problems

It refers to the maintenance and assurance that the data in a database are correct and consistent. Following are the factors related to this issue :

• Data values must satisfy certain consistency constraints that are specified in the application programs.
• It is difficult to make changes to the application programs in order to enforce new constraints.

Security problems

Security can be a problem with a file-based approach because:

• There are constraints regarding accessing privileges.
• Application requirements are added to the system in an ad-hoc manner so it is difficult to enforce constraints.

Concurrency access

Concurrency is the ability of the database to allow multiple users access to the same record without adversely affecting transaction processing. A file-based system must manage, or prevent, concurrency by the application programs. In a file based system, when an application opens a file, that file is locked. This means that no one else has access to the file at the same time.

In database systems, concurrency is managed thus allowing multiple users access to the same record.