How is request distribution among Redis nodes implemented for data retrieval?

In Redis, the distribution of requests between nodes for data retrieval depends on the cluster architecture and the client.

In the case of Redis Cluster, data is distributed across slots (16,384 slots), and each node is responsible for a specific range of slots. A cluster-aware client calculates the slot based on the request key and directs the request directly to the appropriate node.

If a proxy or load balancer is used, it can redirect requests to the corresponding nodes based on the key.

An example with Python and the redis-py library for working with a cluster:

from rediscluster import RedisCluster

startup_nodes = [{"host": "127.0.0.1", "port": "7000"}]
rc = RedisCluster(startup_nodes=startup_nodes, decode_responses=True)

value = rc.get("mykey")  # The client will determine which node to send the request to
print(value)

Thus, request distribution occurs at the client level, which knows which node is responsible for the required key and directs requests directly, ensuring efficient data retrieval.