Practice Flashcards
Flip to reveal answersWhat is denormalisation?
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 5 Flashcards — Denormalisation
Sign up free to track progress and get spaced-repetition review schedules.
Question
What is denormalisation?
Answer
Deliberately storing some data more than once so that reads need fewer joins and run faster. It is a considered engineering trade, not a mistake.
Question
What does denormalising gain and what does it risk?
Answer
It gains faster reads and simpler queries. It risks the same fact being stored in two places and disagreeing, requires every update to find every copy, and brings back insert and delete problems.
Question
When is denormalising justified?
Answer
When data is read far more often than it is written — reports, dashboards and data warehouses that are loaded in bulk and then only read. Never for frequently-written data such as bookings or stock levels.
Question
How should the risk of denormalising be managed?
Answer
Keep the normalised tables as the authoritative source and rebuild the denormalised copy from them, so there is always one correct version to fall back on.
Question
Why should you normalise before denormalising?
Answer
Because you should design in 3NF, run it, and find out where it is actually slow. Denormalising before a measured problem exists gives away correctness for a speed gain you cannot demonstrate.
Read the notes
Full study notes for Denormalisation
Topic 3.2 hub
Database design
More from Topic 3.2
All flashcards in this topic
Computer Science exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free