Apparently as per their docs (http://docs.clustrix.com/plugins/viewsource/viewpagesrc.action?pageId=1769594 http://docs.clustrix.com/plugins/viewsource/viewpage

Apparently as per their docs (http://docs.clustrix.com/plugins/viewsource/viewpagesrc.action?pageId=1769594 http://docs.clustrix.com/plugins/viewsource/viewpagesrc.acti...) this is true specific to end-user transactions: "Note: serializable isolation not currently available to end user transactions." The Serializeable isolation level is used for data moves within the cluster according to the table referencing isolation levels and row visibility rules.