Denormalization
Definition
Denormalization is a strategy used on a previously-normalized database to increase performance. In computing, denormalization is the process of trying to improve the read performance of a database, at the expense of losing some write performance, by adding redundant data or by grouping data.
Why It Matters
While normalization is generally good, sometimes it can lead to queries that require joining too many tables, which can be slow. Denormalization is a performance optimization technique where you intentionally re-introduce some redundancy to speed up specific, frequent read queries.
Contextual Example
In an e-commerce site, you might want to display the product name on the order history page. Instead of joining to the `Products` table every time, you might store a copy of the `ProductName` directly in the `OrderItems` table. This is redundant, but it makes fetching the order history faster.
Common Misunderstandings
- Denormalization should be done carefully and only after performance analysis shows it is necessary.
- It is a trade-off: you sacrifice data integrity and storage efficiency for read performance.