Compared to a file system, how does a database management system avoid redundancy in data through a database?
In a file system, data redundancy occurs when the same data is duplicated in different places or files. For example, student names may be maintained in multiple files, and the same guardian name may be stored twice. This redundancy is difficult to avoid in a file system and leads to excess storage use.
A Database Management System (DBMS) overcomes this limitation by storing data in a database where data are logically related. Related data can be organised efficiently so that it can be managed in an easy way. Instead of duplicating data across multiple files, a database uses primary keys and foreign keys to establish relationships between tables.
This ensures that data is stored only once, eliminating excess storage use and preventing data inconsistency that arises when same data maintained in different places do not match.
Explanation
The textbook explains that redundancy means same data are duplicated in different places (files), which is difficult to avoid in a file system. The DBMS solves this by storing data where data are logically related, allowing efficient organisation. The context also mentions the use of primary keys and foreign keys (shown in Figure 8.5) to establish relationships between tables, which is the mechanism by which databases avoid redundancy.