1. A method for processing a database command that includes an XPath section with an unmappable path, the method comprising the steps of: splitting the unmappable path into a plurality of path fragments, wherein the plurality of path fragments includes a mappable path fragment and an unmappable path fragment; and replacing the XPath section with a replacement XPath section that specifies operations involving path fragments from the plurality of path fragments, wherein the operations include: a mappable operation whose target is defined by the mappable path fragment; and an unmappable operation whose target is defined by the unmappable path fragment.