改进XISS索引技术的仿真研究

研究了数据库查询优化问题,而XISS索引是XML数据库索引中支持正则路径表达式的典型代表。XISS索引对于长查询路径表达式,要产生大量中间结果,连接操作代价十分高,加大了查询的时间和空间复杂度,导致查询的效率和准确率低。为了提高XML数据库查询效率和准确率,提出一种改进的XISS索引技术。首先引入DTD模式信息,简化编码方式;然后对节点索引结构进行改进,减少中间结果的连接次数,使得查询时间与路径长度无关,提高了查询效率和准确率。最后通过实验对改进前后的XISS索引进行仿真。结果表明,改进的XISS索引缩短了建立索引的时间,加快了查询响应的速度,提高了XML数据库查询的效率和准确率。

Simulation Study on Improved Index Technology for XML Data

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.