【作者】 庄灿伟； 冯少荣； 林子雨； 张东站；

【Author】 Zhuang Canwei,Feng Shaorong,Lin Ziyu,and Zhang Dongzhan (Department of Computer Science,Xiamen University,Xiamen,Fujian 361005)

【机构】 厦门大学计算机科学系；

【摘要】 编码技术是XML查询处理的基础,为适应XML更新需要,近年来提出很多动态编码方法,大致可分为基于位串的编码和基于向量的编码.当XML更新时,动态编码方法应该产生最短位长新编码分配给插入节点.位串编码具有这个性质,而对于向量编码,却是一个难点.以DDE为例,提出了向量编码的最短位长新编码计算方法.该方法将问题建模为整数规划,通过构造所有不可约分数求得最短位长新编码.和原有简单利用向量相加计算新编码相比,优点包括了重用已删编码,降低编码长度,提高查询性能,具有更好查询支持等.更多还原

【Abstract】 Label schemes lay the basis for XML query processing.To meet the need of XML updating, several kinds of dynamic schemes have been proposed,which can be divided into the string-based and the vector-based.When XML updating,a label scheme should produce the label with smallest size for the inserted node.The schemes based on string have this property while the vector based has not.In this paper,we took DDE to propose a method of calculating the label with smallest size for vector schemes.We modeled it as integer programming problem,and got the smallest size by constructing the set of all nonnegative fractions.Compared with the original,the benifits of our method included reusing the deleted labels,reducing the label length,improving the query performance,and having a better query support.更多还原