A Level Computer Science OCR Practice Exam

What is a key disadvantage of creating an index in a database?

1. It decreases the accuracy of data storage

2. It increases the speed of data writing

3. It requires additional writes and storage space to maintain

4. It eliminates the need for primary keys

The correct answer is: It requires additional writes and storage space to maintain

Creating an index in a database indeed comes with the disadvantage of requiring additional writes and storage space for maintenance. When an index is created, it essentially creates a separate data structure that maps the indexed fields to the corresponding records in the database. This map is useful for speeding up queries, as it allows the database management system to quickly locate the relevant records without scanning the entire table. However, this added structure means that every time a record is inserted, updated, or deleted, the index must also be updated to reflect these changes. This requires extra write operations and consumes additional storage space, leading to potential performance trade-offs, especially in scenarios with frequent data modifications. Thus, while indexes improve read operations and query performance, the overhead associated with maintaining them can be significant, particularly in write-heavy applications.