1. In a database system, a method for performing a schema evolution operation using partial data copy, the method comprising: determining a portion of data in XML documents associated with a first version of an XML schema to convert to conform to a second version of the XML schema; wherein the first version of the XML schema is associated with a first database representation, a portion of which includes one or more first database structures; wherein the portion of data in the XML documents is stored in said one or more first database structures; wherein the second version of the XML schema is associated with a second database representation, a portion of which includes one or more second database structures; wherein the first database representation is different from the second database representation; and populating at least one of the one or more second database structures with a copy of said portion of data.