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Data & Analytics · Foundational

Database Normalization

The process of organizing tables to reduce redundancy and prevent update anomalies by applying normal forms.

Definition

Normalization decomposes tables based on functional dependencies so that each fact is stored once. The usual target for OLTP systems is third normal form (3NF) or Boyce-Codd normal form (BCNF). It improves write integrity but requires more joins for reads, which is why analytic models are often denormalized.

Example

Moving customer address data out of an Orders table into a Customers table.

Exam tip

Normalize for OLTP (write integrity); denormalize for OLAP and reporting (read speed). Don't confuse this with ML feature normalization.

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