Backend · Junior · Theory

Why does a backend need a cache, and what problems show up when you add one?

~4 min by voice

How to approach it

This checks whether the candidate understands why a cache is needed in practice (speed and taking load off the database) and sees the cost of that choice: stale data, invalidation, memory limits and load spikes on misses.

Have you seen this question in a real interview?

Answers0

Avg. score—

Strong—

Practiced0

Topics

caching

Similar questions

Перед базой стоит кеш в Redis с карточками товаров, TTL — пять минут. Расскажите, как бы вы организовали чтение и обновление, как кеш может разойтись с базой, и что произойдёт, когда истечёт TTL у очень популярного ключа. Mid-level Write a memoizeAsync function. It takes an async function of a string key and a cache time to live in milliseconds, and returns a wrapper: a repeated call with the same key doesn't go to the network, concurrent calls share a single request, and errors aren't cached. Senior You added a cache in front of the database for product cards, and users started complaining that they see outdated prices. How should you set up caching to avoid this? Mid-level Design a URL shortener: a user submits a long URL and gets a short one, and following the short link redirects to the original. Mid-level You put a cache in front of a heavy database query. What problems do you expect with this cache under high load, and how will you solve them? Senior

Answer by voice

The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.

Best with headphones · ~4 min