Thanks for your response.
The number of attributes/values will be different for each order item, some may have only 2-3, others may have a hundred. Say I can have at most 100 attributes, does that mean I need to include every single attribute in the schema collection? Also, would it make sense to include price in the XML column, since it is also an attribute of order_item? What about the primary key child_order_item_id?
<orderitem_attribute>
<attribute1>asd fgh jkl ...</attribute1>
<attribute2>$99.95</attribute2>
<attribute3>1</attribute3>
<attribute4>Attribute 0000004</attribute4>
</orderitem_attribute>
Thank you.