利用视图重写技术优化XML查询

Apply the Technology of Rewriting View to Optimize XML Query

规则路径查询,其长度是任意的,这就意味着对数据库的任意多次访问,这样的代价是很昂贵的。我们采用视图重写技术,通过对某些经常使用的路径查询定义视图,从而减少了对某些高频使用的路径查询的重复搜索,最终提高了查询效率。我们的视图不但可以对路径查询进行重写,而且还可以对树查询进行混合重写。我们设计了一个使用动态规划策略实现的视图重写算法。

With the advent of XML standard, XML is widely used in exchanging data on the Web.More and more people is taking up with optimizing XML query.In fact, the common feature of the query languages for semi_struc- ture data is the use of regular path expressions to query the data, the length of the paths is arbitrary, and in other words, it means frequently accessing the database. In this paper, we propose a technology of rewriting view. Many queries are used repeatly, rewrting view can improve XML query efficiency by reducing the times of scaning the docu- ments repeatly.