itsual Caching Strategies
Overview
Caching can dramatically improve performance and reduce load, but incorrect caching introduces subtle bugs and stale data problems.
When to Use
- Hot read paths
- Expensive computations or external calls
- Reviewing existing cache usage for correctness or effectiveness
Key Questions
- What is the cost of a cache miss vs. a stale read?
- What is the invalidation or expiration strategy?
- Is the cache local, distributed, or both?
- How do we observe hit rates and stampede behavior?
Common Patterns
- Cache-aside
- Read-through / write-through
- Write-behind (use with caution)
- Time-based expiration + explicit invalidation
- Request coalescing / singleflight to prevent stampedes
Principles
- Cache what is expensive and relatively stable
- Make consistency requirements explicit
- Prefer simple invalidation over complex speculative caching when correctness matters
- Monitor hit rate, latency, and error rates
Verification
- Stale data behavior is understood and acceptable
- Cache failures degrade gracefully
- Hit rates and effectiveness are measurable