Hash slots distribution in Redis

Introduction

Hash slots help Redis split data across multiple servers evenly. This makes Redis faster and able to handle more data.

When you want to store lots of data and need to spread it across several Redis servers.

When you want Redis to automatically decide where to put each piece of data.

When you want to make sure your Redis cluster stays balanced and fast.

When you add or remove Redis servers and want data to move smoothly between them.

Syntax

Redis

Redis Cluster uses 16384 hash slots numbered from 0 to 16383.
Each key is assigned to one hash slot using a hash function.
The command to see slot allocation is: CLUSTER SLOTS

Redis divides keys into 16384 slots to distribute them.

The CLUSTER SLOTS command shows which server handles which slots.

Examples

This command lists all hash slots and the Redis nodes responsible for them.

Redis

CLUSTER SLOTS

When you get a key, Redis uses the hash slot to find the correct server automatically.

Redis

GET key
# The key is hashed to a slot, and Redis finds the right node to get the value.

Sample Program

This command returns the current distribution of hash slots across the cluster nodes.

Redis

CLUSTER SLOTS

Important Notes

Hash slots make Redis cluster data distribution simple and efficient.

Each key always maps to the same slot unless the cluster changes.

Understanding hash slots helps when scaling Redis or troubleshooting cluster issues.

Summary

Redis uses 16384 hash slots to split data across servers.

The CLUSTER SLOTS command shows how slots are assigned.

Hash slots help Redis find data quickly and balance load.