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This article introduces the relevant knowledge of "what is Redis Cluster". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

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(1) what is Redis Cluster?

Redis Cluster is a distributed solution of Redis, which is officially launched in Redis version 3.0, which effectively solves the needs of Redis distribution. When you encounter bottlenecks such as stand-alone memory, concurrency and traffic, you can use Cluster architecture to achieve load balancing.

The bottleneck encountered in the use of Redis

We often encounter some problems in our daily use of redis:

(1) the problem of high availability and how to ensure the continuous high availability of redis.

(2) for the capacity problem, the memory of a single instance redis cannot be expanded indefinitely. When it reaches 32 GB, it enters the 64-bit world and its performance degrades.

(3) for concurrency performance issues, redis claims to be 100000 concurrency of a single instance, but it also has an end.

Advantages of Redis-Cluster

(1) official recommendation, no doubt.

(2) decentralized, the cluster can increase by up to 1000 nodes, and the performance expands linearly with the increase of nodes.

(3) easy to manage, you can add or remove nodes, move slots and so on.

(4) simple and easy to use.

(2) data Distribution Theory and data Partition of Redis

Distributed database mainly solves the problem of mapping the whole data set to multiple nodes according to partition rules, that is, dividing the data set into multiple nodes, and each node is responsible for a subset of the whole data. Common partitioning rules are hash partitioning and sequential partitioning. Redis Cluster uses hash partitioning rules.

Virtual slot partition skillfully uses hash space, using well-dispersed hash functions to map all data to a fixed range of integers, which are defined as slots (slot). For example, the range of Redis Cluster slots is 0 ~ 16383. Slot is the basic unit of data management and migration in the cluster.

Redis Cluster uses virtual slot partition, and all keys are mapped to 0 ~ 16383 according to the hash function. The formula is slot = CRC16 (key) & 16383. Each node is responsible for maintaining part of the slot and the key value data mapped by the slot.

(3) the architecture of Redis Cluster

Let's take six nodes as an example to introduce the architecture of Redis Cluster, as shown in the following figure. Among them: three are master nodes and the other three are slave nodes.

This is the end of "what is Redis Cluster". Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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