What Are Big Keys and Hot Keys?

Updated on 2024-12-11 GMT+08:00

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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.

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.

Parent topic: Big/Hot Key Analysis

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