Denormalization
Deliberately storing the same fact in more than one place, usually by combining related tables into one wide table, so the data is easier or faster to read.
The cost is that the copies can drift apart. If a customer's city is repeated on every order row, a partial update leaves one customer with two cities.
Where it comes up
- Duplicate keys with conflicting valuesTwo rows share an identifier that should be unique, but disagree on other fields.
See also
- NormalizationConverting values to a common form or scale. The word is used for text (one case, one spacing), for numbers (a common range), and for database design (removing repetition).
- JoinCombining two tables by matching rows that share a value, such as attaching customer names to orders through a customer ID.
- Flat fileA plain file that holds one table, usually one record per line, with no links to other tables. A CSV export is the most familiar example.