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Understanding Cache Performance in ResourceBuddy

Why the Hit Rate Appears Low

The cache hit rate you're seeing (19.6% - 28%) is actually normal and expected for a recently started cache system. Here's why:

How Caching Works

  1. First View = Always a Miss

    • When you view a resource for the first time, it's not in cache
    • The system fetches it from ResourceSpace and stores it
    • This counts as a "miss"

  2. Subsequent Views = Hits

    • When you view the same resource again, it's served from cache
    • This is much faster (1-2ms vs 100-500ms)
    • This counts as a "hit"

  3. Page Loads Fetch Multiple Resources

    • A typical page might load 20-50 resources at once
    • If these are new resources, they all count as misses
    • This significantly impacts the overall hit rate

Your Current Cache Performance

Based on the metrics:

  • 120 resources are fully cached
  • 211 Redis hits vs 99 misses (68% Redis efficiency)
  • 57 SQLite cache hits vs 138 misses
  • All subsequent views of cached resources are fast

Why This is Actually Good

  1. Redis is Working Well

    • 68% hit rate in Redis
    • All 120 resources are in Redis memory
    • Sub-millisecond response times for cached items

  2. Cache is Building Up

    • Every new resource viewed gets cached
    • Hit rate improves over time
    • Popular resources get served faster

  3. Performance Benefits

    • Cached responses: 1-2ms
    • Non-cached responses: 100-500ms
    • 50-250x faster for cached content!

Expected Hit Rates

  • Fresh cache (first day): 10-30% hit rate
  • Warm cache (1 week): 40-60% hit rate
  • Mature cache (1 month): 70-90% hit rate

How to Improve Hit Rate

  1. Pre-warm the Cache

    # Prefetch popular resources
curl -X POST http://localhost:8000/prefetch \
  -H "Content-Type: application/json" \
  -d '{"resource_ids": [1,2,3,4,5], "include_files": false}'

  2. Increase Redis TTL

    • Current: 5 minutes (300 seconds)
    • Recommended: 1-24 hours for metadata

  3. Enable Browser Caching

    • Backend already sets proper cache headers
    • Browser will cache images locally

Monitoring Tips

  1. Focus on Redis Hit Rate

    • More meaningful for hot data
    • Should be 60-80% when warm

  2. Watch Response Times

    • Cache hits: < 5ms
    • Cache misses: > 100ms

  3. Track Popular Resources

    • Most accessed list shows what's hot
    • These should have near 100% hit rate

Conclusion

Your cache is working correctly! The "low" hit rate is because:

  • You're viewing many different resources (exploring)
  • The cache is still warming up
  • Each first view is a miss by design

As users revisit popular content, the hit rate will naturally improve. The important thing is that repeated views are fast, which they are!