Handling hot shards

This post details how PlanetScale's Neki (built on Vitess) handles 'hot shards' by allowing users to adjust sharding strategies, scale individual shards, or isolate large tenants. It explains the concept of hot shards arising from uneven data distribution and the importance of a declarative data topology for reasoning about data placement. The post outlines three mitigation strategies: scaling up individual shards, isolating large tenants by adjusting key ranges, and resharding specific tables to a more appropriate shard key. It highlights the zero-downtime resharding capabilities of Neki, drawing parallels to Slack's experience with Vitess.