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System Design

Caching

Scope

Techniques for reducing read latency and backend load by storing derived or duplicated data closer to consumers.

Why This Topic Exists

Caching is often the first scaling lever engineers pull—and one of the fastest ways to introduce correctness, consistency, and operability bugs.

Core Tradeoffs

  • Latency vs correctness
  • Freshness vs availability
  • Memory usage vs recomputation
  • Simplicity vs control

Common Failure Modes

  • Stale or inconsistent data
  • Cache stampedes / thundering herd
  • Silent cache corruption
  • Cache dependency becoming a single point of failure

Interview Signals

Strong candidates talk about invalidation strategies, failure handling, and load behavior—not just Redis.

  • Databases
  • Consistency
  • Load shedding