Research on recursive query over XML data stream based on pushdown automation

For descendant axis (//) and predicate ([]) structural features of XPath with different depths of the XML data stream recursive query processing problem, a method based on pushdown automation is presented. It made the kinds of step transform into the corresponding processing modules, then these modules are combined by the algorithm, the top-down tree query model is built. Because the multi-match will occurred in the query processing, which will produce a large number of matching patterns, the model save and check those matching modules by the effective matching strategy and cache operating, successfully completed the recursive query over XML data stream. Finally, the experimental results show that the proposed method is better than the traditional method.