Why didn't anybody tell me about Redis hash slots?

The article shows how a seemingly simple caching optimization for route estimation in a high-volume delivery system was undermined by Redis Cluster hash-slot behavior, turning intended batched reads and writes into many small round trips. For CIOs and technology leaders, the key takeaway is that infrastructure details like sharding and key design can materially affect latency, cost, and scalability—especially in distributed systems where application patterns must align with platform constraints.