I can understand.
Say for example, we have 5 node cluster. If a node has some patching activities to be performed, in that context, only that node can be detached form the cluster and perform the necessary actions on that node. Once the activities on the node is finished and add the nodes back in the same cluster. Since it is distributed, business continuity is still maintained. No outage to the application as the cluster is still functioning. Is that you mean to convey?
Is it possible to upgrade the version of CockorachDB in one node in the Cluster and others still have the older version. Would that entire cluster functioning normally?
Also one more statement would like to highlight “Run schema changes in the background” … What is meant by the statement ?
What all are Schema changes statements performed in the background?