Normalization vs Denormalization

A product is called "Wireless Mouse", and its name appears in 40,000 order rows. Marketing renames it to "Wireless Mouse Pro".

If the name lives in one place, and every order points at it, the rename is one update. If the name was copied into all 40,000 rows to make order pages load faster, the rename is 40,000 updates. Miss one, and the system now stores two different names for the same product.

That is the whole trade-off. Normalization stores each fact exactly once. Denormalization stores copies of a fact on purpose, so reads do less work