With the advent of XML as a standard for data representation and exchange on the Internet

storing and querying XML data becomes more and more important.This poses a new challenge concerning indexing and searching XML data

because conventional approaches no longer apply to XML data.A variety of novel indexing techniques for efficiently retrieving the results have been proposed in the recent literature.However

relative path based query still needs to be more efficient.A containment based indexing scheme for XML data is proposed

which makes full use of the topological structure of the XML documents and can be more efficient to deal with relative paths than previous methods.The key properties of the scheme are as follows:(1)Transform relative paths to absolute paths by using the topological structure of the XML documents instead of DTD or XML Schema;(2)Apply a numbering scheme to the topological structure

which can quickly determine the ancestor-descendant relationship between elements in the hierarchy.Experimental results from the prototype system implementation shows that the scheme can be used to process XML queries with regular path expressions(especially relative paths)faster than previous approaches.