摘要
针对Deep Web环境中存在的失败查询,提出了一种有效的查询松弛策略.所有Deep Web资源按查询接口属性分组,组成全局数据源关系图(DRG);针对特定查询将DRG转换为对应该查询请求的数据源关系图;利用该DRG,按照特定的规则进行查询松弛和执行处理.针对查询松弛导致的部分结果可能与用户查询请求的相似度较低的问题,提出先通过Skyline方法对结果进行筛选,然后再根据各个结果实例与用户查询的相似度进行Top-k排序,最后将最接近用户要求的结果集返回给用户.通过实验验证了提出的查询松弛策略的有效性.
In the process of query in Deep Web data integration system,it is hard to avoid the so-called failed query that brings unsatisfactory result. So it is more cooperative to modify the raw query to return non-empty result set than to notify the user that there is no result corresponding to the query at all. Inspired by the observations and analysis on deep Web,a query relaxation solution applied in a deep Web data integration system is proposed in this paper,in which,all the Deep Web sources are grouped based on their query interface attributes and constructed as a global database relationship graph （DRG）,the global database relationship graph （DRG） is transformed to database relationship graph fitting a specified query,and then the query is relaxed and executed based on the DRG. However,because of query relaxation the amount of the results from the data sources may be very large,and part of them may be not similar to the user＇s query. Therefore after receiving the results from the data sources,a part of the results is first selected by using the skyline method,and then is sorted based on the similarity between the results and the user＇s query,Finally the results satisfying the user＇s requirement are returned to the user. Experiments demonstrate the availability of the query relaxation strategy.
出处
《计算机研究与发展》
EI
CSCD
北大核心
2010年第1期88-95,共8页
Journal of Computer Research and Development
基金
国家自然科学基金项目(60673139
60973021)
国家"八六三"高技术研究发展计划基金项目(2008AA01Z146)
