DataTerminology.comNEW
A request served directly from a cache, avoiding a call to the origin system.
DESCRIPTION
Cache hits improve performance and reduce origin load by serving previously stored responses. They lower latency, cut bandwidth costs, and can reduce tail latency for end users. Cache hit ratio is a key metric indicating how efficiently a cache serves content. Hits occur in application caches, reverse proxies, databases, and CDNs. Effective TTLs, invalidation strategies, and cache keys are essential. Risks include serving stale content if validation is mismanaged.
ALTERNATIVE DEFINITIONS
Cloudflare
A cache hit occurs when the requested content is found in a cache and can be served to the user without sending the request to the origin server.
Emphasizes CDN context and origin avoidance.
NGINX
A cache hit occurs when NGINX can send a response from its cache.
Highlights reverse proxy server behavior.
AWS
Cache hit ratio is the proportion of viewer requests served from CloudFront edge caches.
Focuses on the metric related to cache hits in a CDN.
RELATED TERMS
Cache Invalidation Cache Eviction Cache Hit Ratio TTL Content Delivery Network Edge Caching LRU Cache Stale-while-revalidate Initialization
COMPETING TERMS
KNOWLEDGE AREAS
Software Engineering Infrastructure Observability & Telemetry Real-time & Streaming Data Data Storage & Operations
TARGET AUDIENCE
Software Developer DevOps Engineer Cloud Architect Software Architect Data Engineer
EXTERNAL SOURCES
- Wikipedia - Cache (computing)
- Cloudflare - CDN-focused cache hit overview
- NGINX - Reverse proxy caching guide
- AWS - Cache hit ratio metric
TOP QUESTIONS
Why is a Cache Hit important for application performance?
Cache hits avoid expensive origin calls, reducing latency and load. They improve scalability and lower bandwidth costs, making user experiences faster and more reliable.
Category: Relevancy
How do I measure Cache Hit for my service?
Track cache hit ratio (hits divided by total requests). Monitor per-path keys, TTL effectiveness, and validation logic to understand performance impacts.
Category: Requirements
What are common mistakes around Cache Hit optimization?
Using overly broad cache keys, ignoring validation, and setting inappropriate TTLs can cause stale content or low hit ratios. Missing cache hierarchies limits effectiveness.
Category: Mistakes
How does Cache Hit relate to Tail Latency?
Cache hits lower typical and tail latencies by serving content immediately. High-percentile delays often drop when more requests are served from cache.
Category: Example
What strategies increase Cache Hit ratio?
Normalize cache keys, tune TTLs, leverage stale-while-revalidate, pre-warm popular resources, and use hierarchical caches (edge and origin).
Category: Best practices
What is the biggest misunderstanding about Cache Hit?
Many assume more caching always helps; misconfigured caches can serve stale or incorrect content and hurt reliability if validation isn’t designed well.
Category: Misunderstanding
What risks accompany optimizing for Cache Hit?
Aggressive caching can increase staleness risk, break personalization, and complicate invalidation. Security-sensitive data must be carefully excluded.
Category: Risks
Is a Cache Hit always beneficial?
Generally yes, but for dynamic or personalized content, cache hits may deliver incorrect results if keys or validation are misconfigured.
Category: Opinion
What is a counterpart term to Cache Hit?
Cache Miss is the counterpart, indicating content was not in cache and required origin retrieval.
Category: Alternatives
How do CDNs influence Cache Hit?
CDNs distribute caches closer to users, improving hit ratios for static and cacheable content and reducing round-trip times to origins.
Category: Topic