A Level Computer Science OCR Practice Exam

What does redundancy in database systems primarily refer to?

1. Duplicating fields in multiple tables

2. Storing only unique entries in a database

3. Creating a backup of database data

4. Minimizing data for efficiency

The correct answer is: Duplicating fields in multiple tables

Redundancy in database systems primarily refers to duplicating fields in multiple tables. This occurs when the same piece of information is stored in more than one table. While redundancy can sometimes be intentional for purposes such as data integrity or performance improvement through faster access, it often leads to issues like increased storage requirements and the potential for data anomalies. For example, if an address is stored in multiple tables and needs to be updated, all instances must be updated to avoid inconsistencies. The choice that mentions storing only unique entries would focus on normalization principles, which aim to reduce redundancy rather than affirm its presence. The option about creating a backup refers to data protection practices, which are essential for data recovery but are not directly related to the concept of redundancy in the context of data storage. Minimizing data for efficiency focuses on reducing storage and optimizing database performance, which again is more aligned with normalization rather than redundancy.