Just noticed that :-
“DELETE operation is unsupported on tables without primary key. Also rows in tables without primary key may appear in different order on different nodes. As a result SELECT…LIMIT… may return slightly different sets.”
has been removed from http://www.percona.com/doc/percona-xtradb-cluster/limitation.html but is still present in the pdf manual. Has that limitation been removed and the pdf not yet updated or is the web page wrong?