Cache Invalidation: Keeping Cached Data Correct

Caching speeds up your app, but stale cache can show wrong data. A professional caching strategy always answers one question: When does cached data become invalid? ## Pattern 1: Time-based expiration ```php Cache::remember('top_posts', 60, fn () => Post::top()->get()); ``` Simple, but not always accurate. ## Pattern 2: Forget cache when data changes ```php Post::created(function () { Cache::forget('top_posts'); }); ``` ## Pattern 3: Versioned cache keys ```php $key = 'top_posts:v' . Cache::get('top_posts_version', 1); ``` When posts update, bump the version. ## Graph: Invalidation flow ```mermaid flowchart TD A[Data Updated] --> B[Invalidate Cache] B --> C[Next Request Rebuilds Cache] ``` In the next tutorial, we will implement file downloads and streaming large exports.