函数依赖对商覆盖立方体生成效率的影响

提出一种新的商覆盖立方体生成算法DDFS。指出在基本表维属性之间可能存在函数依赖；分析了这种函数依赖对DFS算法的影响；按照决定子在前的原则调整了DFS算法对基本表进行水平分割时所依据的维属性的顺序；对于存在函数依赖的维属性对，节省了判断是否存在类函数依赖的操作。采用weather数据集进行的实验结果表明，采用DDFS计算商覆盖立方体所需时间仅为采用DFS算法时的76%。得出DDFS较之DFS可以缩短商覆盖立方体生成时间。

Computing cover quotient cube considering functional dependency in base tables

This paper proposes a new algorithm DDFS to compute cover quotient cube.Functional dependency between base attributes are considered to improve the efficiency of computing.When the base table is partitioned with a particular attribute order，the attribute functionally depended is considered with a priority.For the attributes pair where there is a functional dependency，the cost of finding the congeneric functional dependency is retrenched.Experimental result on the dataset weather shows that the computing time associated with DDFS is only 76% of that with DFS.There is a conclusion that DDFS can shorten the time of computing cover quotient cube，compared with DFS.