Basic Notions
Basic Notions
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DOI：
10.4018/978-1-59140-053-0.ch001
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
M. Rafanelli
中科院分区：
文献类型：
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作者：
M. Rafanelli
本章通过参考文献中给出的不同定义，介绍了关于多维（聚合）数据库的基本概念。它说明了微观、宏观和元数据的重要概念;给出了聚合过程的正式定义，讨论了维度和维度层次结构的概念;描述了多维聚合数据结构，区分了简单、复杂和复合结构;说明了不同类型的空值;并讨论了多维聚合数据之间存在的差异和相似之处，（通常称为统计数据，因为它们主要由统计人员使用）和由不同数据立方体表示的多维数据的联机分析处理（OLAP），还讨论了OLAP和聚合多维数据库所需的维度和度量的不同（对称和非对称）处理。最后讨论了这类数据的图模型和表模型，并给出了OLAP术语的定义。
This chapter presents the basic notions regarding multidimensional (aggregate) databases by referring to different definitions given for them in the literature. It illustrates the important concepts of micro, macro, and metadata; presents a formal definition of the aggregation process, discussing the concepts of dimension and dimension hierarchies; describes the multidimensional aggregate data structure, distinguishing between simple, complex, and composite structure; illustrates the different types of null values; and discusses differences and similarities which exist between multidimensional aggregate data (generally called statistical data because they are used mainly by statisticians) and the On-Line-Analytic Processing (OLAP) of multidimensional data represented by different data cubes, also discussing the different (symmetric and nonsymmetric) treatment of dimensions and measures required by OLAP and aggregate multidimensional databases. Finally it discusses a graph model and a tabular model for this kind of data, and gives a set of definitions regarding the OLAP terminology.