摘要
讨论在关系数据库中利用 SQL 语句实现 XML 查询的问题 .首先提出了一个利用映射信息 (映射图 )将带正则路径表达式的 XML 查询重写为一组简单路径查询的算法 .该过程中的一个关键问题是 Kleene表达式不能直接利用映射图重写 ,为此 ,提出了利用路径实例的统计信息来扩展 K leene表达式的算法 .然后 ,进一步描述了将简单路径表达式查询重写为 SQL 查询的方法 .这些算法在 XML-关系系统原型 VXML R中实现 .
In this paper, a problem is studied, which evaluates XML queries using SQL statements in relational database systems. At first, an algorithm is proposed, which rewrites a regular path expression based XML query as a group of simple path expression based queries using mapping information(mapping graph). A key problem in this process is that a Kleene expression cannot be rewritten using mapping graph directly. To handle this problem, statistical information of path instances is gathered to expand Kleene expressions. After that, an approach to rewrite a simple path expression into a SQL statement is described. The approaches presented are implemented in a virtual XML relational prototype system VXMLR. A preliminary performance study shows that the approaches are very effective.
出处
《计算机研究与发展》
EI
CSCD
北大核心
2001年第4期422-429,共8页
Journal of Computer Research and Development
基金
国家自然科学基金!(6 0 0 0 30 16
6 0 0 0 30 0 8)
国家重点基础研究"九七三"基金项目!(G19980 30 4-14 )资助
关键词
映射图
关系数据库
数据查询
SQL
XML
mapping graph, Kleene path expression, RPE SPE rewriting, SPE SQL rewriting
