Which of the following is a direct effect of normalization?

• A. Increases data redundancy
• B. Eliminates the need for data modeling
• C. Decreases data redundancy
• D. Eliminates all anomalies

Answer: (C)

Normalization is about organizing data so that it sits in related, non-redundant tables, reducing duplication and dependency between data items. The direct effect of this approach is a decrease in data redundancy, since each fact is stored in one place and linked as needed rather than repeated in multiple rows. This reduction in duplication also helps prevent update, insert, and delete anomalies, because changes are made in a single place rather than across many copies. Of course, normalization doesn’t automatically eliminate every possible anomaly in every situation, and it doesn’t remove the need for thoughtful data modeling or consider performance trade-offs from the necessary joins. The ideas that redundancy increases, that data modeling isn’t needed, or that all anomalies are eliminated aren’t accurate descriptions of normalization’s direct effect.