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System Design · Concept

Cache

A cache stores recent query results so repeated requests can return quickly without repeating expensive backend work. An LRU policy removes the least recently used entry when the cache is full.

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Syntax

get(query) -> result | None
set(query, results)

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  • cache-aside
  • time to live (TTL)
  • Memory Cache
  • Redis
  • Memcached
  • consistent hashing
  • Load Balancer
  • Query API server

Source: system-design-primer/solutions/system_design/query_cache/README.md at ae9bbd7b02d90b9866215de185217d33f39ab733 · donnemartin/system-design-primer. Checked 2026-11-03.