ReferenceIncidentsEra 5 · Series CHot keyA celebrity posted. 30% of reads asked for one key, and its shard saturated.What happens#A celebrity posted. 30% of reads asked for one key, and its shard saturated.How to prevent it#Split hot keys across shards and cache them in the App Servers.The postmortem opens the first of these that you do not own yet:Hybrid fan-outEngineering terms#Fan-outFan-out on writeHot keySharding