Supporting selection-projection XQuery processing based on encoding paths

Providing an efficient way to support XML query processing has become a very important issue. A system called XQP (XQuery Processor) is proposed in this paper to meet the need. XQP represents XML data using the encoding of element tags (ET-encoding) and the encoding of element contents (EC-encoding). The path expression presented in the input XQuery statement could be therefore represented as a sequence of encodings, termed as the ET-encoding path. We could similarly get EC-encoding paths by applying the path expression to the XML data. XQP accepts a typical XQuery statement, which consists of the selection construct to impose constraints, and the projection construct to return the content of an arbitrary element. To process an XQuery statement, XQP will first retrieve the EC-encoding paths which satisfy the selection constraint and the projection requirement respectively, and then perform matching on them to obtain the correct data. Using encoding paths could simplify and fasten the matching process. Several experiments are conducted, and the results show the efficiency and scalability of our approach.