Help Center/ Distributed Cache Service/ FAQs/ Big/Hot Key Analysis and Expired Key Scan/ What Are Big Keys and Hot Keys?
Updated on 2025-10-23 GMT+08:00
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What Are Big Keys and Hot Keys?

Term

Definition

Big key

There are two types of big keys:

  • Keys that have a large value. If the size of a single String key exceeds 10 KB, or if the size of all elements of a key combined exceeds 50 MB, the key is defined as a big key.
  • Keys that have a large number of elements. If the number of elements in a key exceeds 5000, the key is defined as a big key.

Hot key

A hot key is most frequently accessed, or consumes significant resources. For example:

  • In a cluster instance, a shard processes 10,000 requests per second, among which 3000 are performed on the same key.
  • In a cluster instance, a shard uses a total of 100 Mbits/s inbound and outbound bandwidth, among which 80 Mbits/s is used by the HGETALL operation on a Hash key.