You can try 3 methods:
Method 1
execute on each node until all nodes are altered:
set wsrep_osu_method=‘RSU’;
set wsrep_osu_method=‘TOI’;
Method 2
shutdown one node
start the node without wsrep plugin
run the alter
restart the node and let it join the cluster
do the same on other nodes
Method 3
Use pt-online-schema-change [url]https://www.percona.com/doc/percona-toolkit/2.2/pt-online-schema-change.html[/url]
For 1 and 2, direct all apps to the nodes that aren’t running the alter.