Database Rate Limiting: The Missing Piece After a Circuit Breaker

This is an extension to my previous post on Circuit Breakers. It only decides: "Should I even try calling Redis?" When the circuit is open, your application executes the fallback. For many systems, that fallback is the database. Request │ Circuit Breaker (Open) │ Database And that's where the real problem begins. The Database Becomes the New Bottleneck Imagine your system normally handles: 100K requests/sec Redis serves 99K Database serves 1K Redis suddenly goes down. Without any protection: 100K Requests ↓ Database 💥 Your database was never designed to handle the entire production workload. A circuit breaker saved you from Redis timeouts—but it didn't save your database. The Solution: A DB Rate Limiter Instead of letting every request reach the database, the application enforces a limit. if circuitBreaker.IsOpen() { if !dbRateLimiter.Allow() { return 503 } return db.Get(key) } If