Why Is "Error in execution" Returned When I Access Redis?

Symptom: "Error in execution; nested exception is io.lettuce.core.RedisCommandExecutionException: OOM command not allowed when used memory > 'maxmemory'" is returned during a Redis connection.

Analysis: An out-of-memory (OOM) error indicates that the maximum memory is exceeded. In the error information, the "maxmemory" parameter indicates the maximum memory configured on the Redis server.

If the memory usage of the Redis instance is less than 100%, the memory of the node where data is written may has reached the maximum limit. Connect to each node in the cluster by running redis-cli -h <redis_ip> -p 6379 -a <redis_password> -c --bigkeys. When connecting to a replica node, run the READONLY command before running the bigkeys command.