What is the term for adding redundant data to improve query performance?

The correct answer is denormalization. This term refers to the process of intentionally adding redundant data into a database to enhance the performance of queries. By reducing the number of joins needed to retrieve related data, denormalization can lead to faster query execution times. This is particularly useful in scenarios where speed is more critical than maintaining the utmost integrity of the data model.

Normalization, on the other hand, is the practice of organizing data to minimize redundancy and dependency, which is contrary to the goal of denormalization. Indexing is a method of creating data structures that allow for quick lookups of information but does not involve adding redundant data to the database. Data warehousing refers to a system used for reporting and data analysis that aggregates data from different sources, which also does not specifically describe the addition of redundant data to improve query performance.