DSA TrainerSystem Design · Unit 8
Caching
Picture a homepage that shows the ten most popular products. Every time someone loads it, the server asks the database for those ten products, the database does the same sorting work it just did a millisecond ago for the last visitor, and hands back the same answer. A million visitors an hour means a million identical questions to the database, all with the same reply.
A cache is a small, fast place to keep the answer to work you have already done, so the next person who needs it gets it instantly instead of making the database do the job again. That is the whole idea: store the result of something expensive close to where it is needed, and reuse it.
This unit is not about memorizing cache brands. It is about the judgment an interviewer is actually testing: recognizing the kind of problem a cache solves, knowing the one big price you pay for it, and being able to say why you would or would not add one.
The rest of the System Design course is premium
The first two units are free, and this is where the gate sits. Unlocking premium opens this unit and everything else in both courses:
- ✓This unit: 5 prediction-first lessons, 3 applied drills, and a 5-question graded test
- ✓All 20 System Design units, caching to CAP & consistency
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