Definition
A single cache or partition key getting a huge share of requests (e.g. a viral item).
How it works
Concentrates load on one node and can overwhelm it even when the cluster has spare capacity. Mitigations: replicate the key to several nodes, add a small client-side/local cache, or split it (key + random suffix). Closely related to the hot-shard problem one level down.
Common questions
What is Hot Key?
A single cache or partition key getting a huge share of requests (e.g. a viral item).
How does Hot Key work?
Concentrates load on one node and can overwhelm it even when the cluster has spare capacity. Mitigations: replicate the key to several nodes, add a small client-side/local cache, or split it (key + random suffix). Closely related to the hot-shard problem one level down.
What is Hot Key used for in system design?
Concentrates load on one node and can overwhelm it even when the cluster has spare capacity. Mitigations: replicate the key to several nodes, add a small client-side/local cache, or split it (key + random suffix). Closely related to the hot-shard problem one level down.