What is denormalization and when would you use it?

Short answer: Denormalization is the process of combining tables that were previously normalized. This introduces redundancy to optimize read-heavy operations. When to use: Performance Optimization: Useful for applications where read speed is crucial and the overhead of complex joins needs to be minimized. Reporting and Analytics: When querying large datasets for reports or aggregations.

Real-world example (ShopNest)

Product and Category are separate tables (normalized). The order line stores product id + price snapshot—not a giant duplicated product blob.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.