16. A computer readable medium having stored thereon instructions for performing the method of querying a document containing hierarchical information that includes parent nodes and descendent nodes, comprising: locating a first parent node in the document by using a mapping specification; determining if the first parent node satisfies a query; and fetching from the document nested descendent nodes relating to the first parent node in response to determining that the first parent node satisfies the query, wherein the locating the first parent node comprises parsing only parent nodes in the document.
18. The computer readable medium of claim 16 , further comprising: upon fetching a last nested descendent node relating to the first parent node, locating a second parent node in the document by using the mapping specification; storing the second parent node in the first relational storage area; fetching from the document nested descendent nodes relating to the second parent node; and storing the fetched descendent nodes in the second relational storage area, wherein the nested descendent nodes are located by using the mapping specification.