76 Part I EXAM PREPARATION planned denormalization is
76 Part I EXAM PREPARATION planned denormalization is the process of simplifying data and data design to achieve maximum performance and simplicity. This denormalization process involves the planned addition of redundant data. Although both normalization and denormalization are valid, necessary processes, the two achieve opposite goals. They don t by themselves achieve maximum performance and simplicity, though they do strive for a perfect balance between performance (denormalization) and simplicity (normalization). Normalization means no duplicate data. In 1970, Dr. E. F. Codd designed three regulations a relational database adheres to, known as normal forms, and today known as the first, second, and third normal forms. (Normal forms do exceed three, but the first three are the only ones widely used.) The goal of the initial database design is to simplify the database into the third normal form. Before starting to normalize a database, look at the following guidelines: All columns should be decomposed (broken down to their most basic form). Many-to-many relationships should be converted to pairs of one-to-many relationships. This is not part of normalization, but part of the physical implementation. Primary and Foreign Keys should be created and identified. Normalizing a database is seemingly good, but can hamper performance. In many cases a designer has to consider denormalizing a database, which is discussed a little later. The following sections discuss the three normal forms of a database and how to implement them. First Normal Form The first normal form, or 1NF, defines the foundation for the relational database system. Attributes should be atomic, which means that they cannot (or should not) be further broken down, based on the business needs for the use of the attribute. The first normal form defines that all attributes be atomic, which is to say they cannot be decomposed and must be non-repeating. In relational database terms, 1NF states that all attributes must be defined in their singular- most form; which means that attributes must be decomposed and
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