Free Keys, ER and normalization lessonsKeys, ER and normalization · Stage 3 · Normal forms · Step 3
When to denormalize
The cost of joins against the cost of redundancy, and the patterns teams use to break normal forms safely. About 12 minutes.
Which situation justifies storing a copy of a column in another table?
- AA measured read bottleneck, on data that changes rarely, with a defined way to keep the copy in sync
- BAlways, to avoid joins
- CThe column is updated constantly and read rarely
Show the answer
A measured read bottleneck, on data that changes rarely, with a defined way to keep the copy in sync. Read gain against a small, controlled write cost.
4 questions on this idea
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