Caching Invalidation Patterns

Overview

Caching makes applications fast by reusing previously fetched or computed data.

The problem is not storing data in a cache. The hard part is knowing:

• when cached data is still valid
• when it is stale
• what must be refreshed after a mutation
• how broad or narrow an invalidation should be

This is why cache invalidation is a core application design problem, not just a performance trick.

What Invalidation Means

Invalidation means telling the system that cached data should no longer be treated as authoritative.