An XML twig approximate query approach based on query fragment relaxation

To deal with the problem of approximate query over XML documents, this paper proposes an XML twig query relaxation approach. The approach gathers the query history to speculate the user preferences, which is used to calculate the importance for each query fragment of the twig query, and relax the original query according to the sequence of the fragments´ importance. Then, the holistic twig algorithm is used to relax the original twig query, based on the number of query fragments we adopt different relax way. The first fragment to be relaxed must be the least important fragment and thus the most relevant query results can be obtained. Finally, ranking the relevant query results based on their satisfaction degree to the original query and the user preferences. The experimental results demonstrate that the XML twig query relaxation approach presented in this paper has the high recall and precision, and can efficiently meet the user´s needs and preferences as well.