Caching Strategies Cheat Sheet

• 2 Strategies
  • Lazy loading
    • When something is requested from cache and cache misses, cache request it from origin
    • This is the strategy used by CDNs
  • Write-through
    • When origin is updated, update cache at the same time
• Compare 🎓
  • Lazy loading
    • Good
      • Low storage needs = only cache requested data
      • Fault-tolerant = replaced nodes only increases latency but can work normally
    • Bad
      • Cache miss = latency
      • Stale data = no way to update cache when origin data is updated
        • Use TTL or use write-through
  • Write-through
    • Good
      • Up-to-date = no stale data
      • No cache miss penalty
    • Bad
      • Write penalty = every writes incurs writing to both cache and database
      • Faults result in missing data = when node is replaced there will be a time window of data not written to cache thus missing
        • Add lazy-loading
      • Wasted storage = most data are not accessed but will account into cache storage
        • Use TTL
• Strategies not exclusive, and be combined and should

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