| In recent years, the query evaluation of XML data stream has attracted scholars' widespread interest at home and abroad. How to effectively implement a large number of XPath expressions over an XML stream is a hot spot in today's research. At present, many XPath query methods over XML document have been proposed. Most of the ways have based on automata, which can be divided into based on nondeterministic finite automata and based on deterministic finite automata. In addition, there are means that based on index or predicate.For a state of NFA, the same input may occur many state transition. It takes quite a long time to find the next specified state. However, for a state of DFA, the same input will occur determinate state transition, but with the increase of the number of XPath query expression, the number of automata states will rapidly increase, so it need to take a lot of storage space.In this paper, problems existed in XML data stream query processing were discussed and researched. Aiming at the lack of the remaining processing methods of XML document, an index structure and a kind of algorithm which based on the index structure are proposed. The main works of this paper are summarized as follows:(1) In this paper, a novel indexing mechanism--- an index structure of XML document is proposed. Firstly, it extracts the document structure from a given XML document. Secondly, it constructs the index nodes according to the document structure. The index structure of the document is composed of the index nodes.(2)A series of XPath query expression were pretreated by making use of the index structure of the document. The query expression which are matched with the index nodes are marked in the predicate list box of their corresponding index node.(3)In this paper, an algorithm LXPF to solve linear path query is proposed.(4) The algorithm which has been proposed in this paper is compared with the previously proposed algorithm, and the experimental results show its effectiveness. |
PDF Full Text Request