Research On XML Subtree Results Generation

In the environment of the rapid development of network, XML plays an importantrole.There are many ways to get the required information in database system. Keywordquery technology is simple, easy to use and does not need to know the query structure, soit became the main method to get information from XML data. So the research based onXML is more and more important.Firstly,we analysis the shortcomings of the exist algorithms. when these algorithmswant to get the SLCA node, it get in the common-ancestor-repetition problem. When itgenerate the results tree, it need to store a lot of nodes which are not the results.Thesepoints reduce the efficient of the query methods.Secendly, get SLCA node is the first step of XML keyword query. It propose anefficient algorithm named TDSLCA, which processes a given keyword query in atop-down way to get all qualified subtree results. It exam if every node is a SLCA node,thus can avoid the common-ancestor-repetition problem.Thirdly, generate the result tree is the second step of XML keyword query.Considering that existing methods are inefficient in constructing subtree results, Itprocesses a algorithm named TDTMS. It constructs its subtree in a top-down,breadth-first way to quickly prune useless nodes, thus achieves the best time and spacecomplexity.At last, we conduct rich experiments on different database, and the experimentalresults verify the performance benefits of our method in terms of time and space.