摘要
Top-k查询在传统的存储确定性数据的关系型数据库中得到了广泛的应用,但是对于存储不确定性数据的数据库,Top-k查询必须结合元组的分值和不确定性来处理。已有的Top-k查询没有很好地结合元组的分值和不确定性,因此,定义一种新的针对不确定性数据的Top-k查询语义,并且实现了查询算法,在新语义下,计算第i位排名时考虑了第i-1位元组,能够更好地权衡分值和不确定性。不同数据集上的实验显示,该算法是有效的。
Top-k query has been widely applied in traditional relational databases storing the deterministic data,but for the databases storing uncertainty data.Top-k query have to process in conjunction with the score and uncertainty of tuples.Existing Top-k query does not combine them well,therefore a new semantics of Top-k query for uncertainty data is defined,and the query algorithm is implemented.In this new semantics,the tuple at rank i-1 is considered when computing the tuple at rank i,so it better balances the score and uncertainty of tuples.Experiments on different data sets demonstrate the efficiency of the algorithm.
出处
《计算机应用与软件》
CSCD
北大核心
2012年第4期186-187,212,共3页
Computer Applications and Software
