Abstract: XISS index is currently typical delegate supporting regular path expression in XML data index XISS index produces large path expression and the intermediate results for long inctuires, so join operation cost is very high, which increases the complexity of query, affects the query efficiency. In order to improve the XML data query efficiency, the article put forward an improved XISS index Improved XISS index at first introduced DTD schema information to improve the coding method, and then the node index structure was improved, to decrease the intermediate links, make query time not related with path length and improve query efficiency. hhe contrast experiment on the index and the improved XISS was made, and the results show that the improved XISS index decreases indexed time, accelerated inquire response speed and improves the XML data query result.

Key words: Index structure, Query processing, Decomposition of path expressions