Database normalization

Database normalization relates to the level of redundancy in a relational database's structure. The key idea is to reduce the chance of having multiple different versions of the same data, like an address, by storing all potentially duplicated data in different tables and linking to them instead of using a copy. Then updating the address in one place will instantly change all the places where the address is used.

Related Topics:
Redundancy - Relational database

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Well-normalized databases have a schema that reflects the true dependencies between tracked quantities. This means that updates can be quickly performed with little risk of data becoming inconsistent.

Related Topics:
Schema - Dependencies

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In the relational model, formal methods exist for quantifying "how normalized" a database is. These classifications are called normal forms (or NF), and there are algorithms for converting a given database between them.

Related Topics:
Relational model - Algorithms

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Any increase in normalization generally involves splitting existing tables into multiple ones, which must be re-joined each time a query is issued. This can sometimes lead to poor performance, so intentional denormalization is used for applications like online analytical processing. Note that these are not "improvements" to the relational model, rather, they borrow aspects of navigational databases and hierarchical databases that are speedier than their relational kin.

Related Topics:
Denormalization - Online analytical processing - Relational model - Navigational database - Hierarchical database

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