Hi! 各位好！
请问es集群是否可以进行热升级，就是在原集群上添加高版本的新节点，然后再去退役集群上的旧版本的节点
Yes, you can upgrade an Elasticsearch cluster without having to shut it down completely! This process is called "rolling" update, where new nodes with the updated version are added to the cluster little by little, while older nodes are gradually taken out of operation.