You're not supposed to extend the attributes in cr_items, only cr_revisions. Here's what the
docs say about creating attribute tables:
"Note that your extended attribute table must reference the cr_revisions table, not cr_items. As mentioned above, this allows you to maintain multiple revisions of the attribute data in tandem with revisions of the content object itself."
Hopefully somebody knows a way around this, as I can't think of one ...
