An XML indexing structure with relative region coordinate

For most of the index structures for XML data proposed so far, updating is a problem, because an XML element's coordinates are expressed using absolute values. Due to the structural relationship among the elements in XML documents, we have to re-compute these absolute values if the content of the source data is updated. The reconstruction requires the updating of a large portion of the index files, which causes a serious problem, especially when the XML data content is updated frequently. In this paper, we propose an indexing structure scheme based on the relative region coordinates that can effectively deal with the update problem. The main idea is that we express the coordinates of an XML element based on the region of its parent element. We present an algorithm to construct a tree-structured index in which related coordinates are stored together. In consequence, our indexing scheme requires the updating of only a small portion of the index file.