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Beginner~55 min·3 systemsCaching & Read-Heavy Systems
How read-dominated systems use caches, CDNs, and precomputation to make the hot path effectively free.
After this path you will be able to
Design any read-heavy system: identify where to add a cache, choose between CDN and in-process caching, and explain the cache invalidation trade-offs to an interviewer.
Interview approach for this path
- 1.Start by asking: is this a read-heavy or write-heavy system? Caching only helps reads.
- 2.Clarify the cache hit rate you'd need. Below 80% and caching may not be worth the added complexity.
- 3.Name the specific caching strategy: cache-aside, write-through, or write-back, and explain why you chose it.
- 4.Call out the eviction policy: LRU for general use, LFU for skewed access patterns.
- 5.Talk about cache invalidation explicitly. This is where most follow-up questions come from.
- 6.Mention thundering herd and how you'd protect a cold cache on startup or after a node failure.
- 7.Address CDN placement for static and semi-static assets before the interviewer brings it up.
Systems in this path
3 total1
URL ShortenerBeginner·12 min
Hashing, key generation, read-heavy caching.
2
Instagram FeedIntermediate·18 min
Fan-out on write vs read, ranking, CDN.
3
Netflix (Video Streaming)Advanced·25 min
CDN-first, adaptive bitrate, recommendation.
Concepts reinforced throughout