Over-Engineering the Cache Layer
I initially built a complex cache invalidation system when simple TTL-based caching would have sufficed.
I spent too much time building a "sophisticated" cache invalidation system.
The Over-Engineering: - Event-driven cache invalidation - Complex dependency graph - Custom invalidation rules engine - Real-time cache updates
The Reality: - Most cached data has natural TTL (user sessions: 1 hour, content: 24 hours) - Event-driven invalidation added complexity without much benefit - Simple TTL + manual invalidation on critical updates works fine
What I Changed: - Switched to TTL-based caching for most data - Manual invalidation only for critical updates (credit balance) - Removed event-driven system - Much simpler codebase
Lesson Learned: Start simple. Add complexity only when you have a clear, measurable need. TTL-based caching handles 90% of use cases.
What I'd change: I should have started with TTL and only added event-driven invalidation if metrics showed it was needed. The simpler system is easier to reason about and maintain.