If your database is a cluster, then it is still conceptually one database with one schema. You can't migrate one node of your cluster to a new schema version and then move your traffic to it.
If you have real replicas, then still all writes need to go to the same instance (cf. my example of credit card transactions). So I also don't understand how your migration strategy would look like.
blue-green is great for stateless stuff, but I fail to see how to apply it to a datastore.
If your database is a cluster, then it is still conceptually one database with one schema. You can't migrate one node of your cluster to a new schema version and then move your traffic to it.
If you have real replicas, then still all writes need to go to the same instance (cf. my example of credit card transactions). So I also don't understand how your migration strategy would look like.
blue-green is great for stateless stuff, but I fail to see how to apply it to a datastore.