具有多时间粒度的时态多值依赖及时态模式分解方法研究  

Normalization of Temporal Scheme with Respect to Temporal Multivalued Dependency with Multiple Time Granularities

作　　者：郝忠孝[1,2] 李艳娟[1,3] 

机构地区：[1]哈尔滨理工大学计算机与控制学院 [2]齐齐哈尔大学计算机系齐齐哈尔161006 [3]东北林业大学计算机科学与技术学院哈尔滨150040

出　　处：《计算机研究与发展》2007年第5期853-859,共7页Journal of Computer Research and Development

基　　金：黑龙江省自然科学基金项目(F00-06)~~

摘　　要：一个好的数据库逻辑设计目标是消除数据冗余以及插入、删除和更新异常.对于时态数据库,通过具有多时间粒度的时态函数依赖约束对时态数据库进行规范化已有大量研究.基于时态函数依赖和多值依赖理论提出了多时间粒度约束的时态多值依赖(TMVD)等概念,并给出了时态多值依赖的推理规则,对其有效性、完备性进行了证明.由于包含有限个TMVD的TMVD集通常蕴含着无限个TMVD,给出了TMVD的有限推理规则,对其有效性、完备性进行了证明.最后,基于时态多值依赖集提出了时态第四范式,并给出了时态模式的T4NF的无损分解算法,对算法的可终止性、正确性进行了证明,并对时间复杂度进行了分析.The purpose of a good database logical design is to eliminate data redundancy and insertion, deletion and update abnomalies. For a temporal database, its normalization has been widely studied by using contraints of temporal functional dependency with multiple time granularities. Based on the process of normalization of traditional relational database, the concepts of temporal multivalued dependency （TMVD） with multiple time granularities based on temporal functional dependency and the theory of multivalued dependency of traditional relational databases are introduced. An axiomatization for TMVD is given. Because a finite set of TMVDs usually implies an infinite number of TMVDs, the notion of the temporal fourth normal form is introduced, and an axiomation for a finite closure to effectively capture a finite set of implied TMVDs is given, which are essential to the logical design. Temporal fourth normal form with respect to TMVDs is given, decomposition algorithm is presented that gives lossless T4NF decompositions, and the complexion of the algorithm is analyzed. In the meanwhile, the proof of the correctness and termination of the algorithm is given.

关 键 词：时态数据库 时态函数依赖 时态多值依赖 时态第四范式 多时间粒度 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]