Comment 5 for bug 1402338

@Fred,

From mysql_upgrade.c I see:

  /*
    Master and slave should be upgraded separately. All statements executed
    by mysql_upgrade will not be binlogged.
    'SET SQL_LOG_BIN=0' is executed before any other statements.
   */

So, the standard mysql convention seems to ask for separate mysql_upgrade for every node.

Note that, PXC major upgrade states to run mysql_upgrade while it is running with none provider, essentially not replicating it.

Now, if a node is ugpraded and started, while there are other nodes in the cluster with older system tables, then it is required that no system table changes (DML) are made (through add user etc.) unless all nodes are upgraded.