What does redis cluster mean?

Redis cluster is a distributed, fault-tolerant Redis implementation. The functions that can be used by the cluster are a subset of the functions that can be used by ordinary stand-alone Redis. (subset).

There is no central node or proxy node in the Redis cluster. One of the main design goals of the cluster is to achieve linear scalability.

Redis Cluster provides a way to run Redis where data is automatically partitioned across multiple Redis nodes. Redis Cluster also provides a level of availability during partitioning, which is the ability to continue running even if some nodes fail or cannot communicate. However, if a major failure occurs (for example, when most masters are unavailable), the cluster will stop functioning.

Redis cluster is a distributed implementation of Redis. It is a mesh structure, and each node is connected to every other node through a TCP connection.

Now let’s take a look at what goals the Redis cluster has achieved?

Still performs well with 1000 nodes and the scalability is linear. Asynchronous replication is used between clusters, and there is no merge operation.

Acceptable write safety (Write safety) level: The system attempts to save all write operations performed by clients connected to the majority of nodes. However, a small portion of writes will still be lost.

Availability: The vast majority of master nodes are reachable, and for every unreachable master node there is at least one reachable slave node. In this case, the Redis cluster can still perform partition operations.

So is there any functional difference between the Redis cluster environment and the non-distributed Redis environment?

The database of the cluster has only 0 and does not support SELECT.

Since the cluster distributes keys in different slots, copy operations involving multi-key values ​​are not supported, such as unions and intersections in set.

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