Error: redis.exceptions.responseerror moved

Solution

What's Causing This Error

The error message you encountered, "redis.exceptions.ResponseError: MOVED," indicates that the Redis server has informed the client that the requested key has been moved to a different Redis node. This error commonly occurs in Redis cluster setups where data is distributed across multiple nodes.

When a Redis cluster is configured to use slot-based sharding, keys are mapped to specific slots, and each slot is assigned to a particular Redis node. If a client attempts to access a key that belongs to a different slot and is located on a different node, Redis will respond with a MOVED error and provide the client with the correct node where the key resides.

## Solution - Here's How To Resolve It

To handle this error, you need to update your client code to handle key redirection properly. When you receive a MOVED error, you should extract the new node information from the error response and redirect your Redis client to that node for subsequent operations on that key.

Here's an example of how you can handle the MOVED error in Python using the redis-py library:

```python
import redis

Create a Redis client
redis_client = redis.Redis(host='redis_host', port=6379)

Perform a Redis operation that triggers the MOVED error
try:
result = redis_client.get('your_key')
except redis.exceptions.ResponseError as e:
if e.args[0].startswith('MOVED'):
# Extract the new node information from the error response
moved_info = e.args[0].split(' ')
new_host, new_port = moved_info[2].split(':')

# Update the Redis client connection to the new node
redis_client = redis.Redis(host=new_host, port=int(new_port))

# Retry the operation on the new node
result = redis_client.get('your_key')
else:
# Handle other types of Redis errors
raise
```

By handling the MOVED error and updating the Redis client's connection to the correct node, you can ensure that your client code can properly access the Redis keys in a cluster setup.