This newsletter explains the challenges of the "hot shard" problem—when a disproportionate amount of traffic targets a single shard, causing resource saturation and degraded performance. The blogpost outlines practical strategies to address this, such as vertical scaling, adding read replicas or caches, distributing hot keys across more shards, choosing better sharding keys and algorithms, implementing load balancing and queueing, controlling traffic with backpressure, and monitoring the cluster for early detection of issues.

https://newsletter.scalablethread.com/p/how-to-handle-hot-shard-problem