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SSAS几个名词
度量维度(measures group)
在数据方中的一些概念如维度(Dimension),度量(Measure),度量组(measure group),层次(hierarchy),级别(level)是很容易理解的,有个概念 度量维度(measures group)让人理解起来非常困难。
MSDN的解释如下，"A measures dimension is the dimension that contains all of the measures in a cube. A measures dimension is a special type of dimension in which the members are typically aggregated (generally by sum or by count) based on the current member of each dimension attribute with which a specified measure exists"
仔细研究以后发现，其实此处的度量维度就是指所有的度量，换句话说度量被当成了一种特殊的维度，这个维度如果有层次结构的话，他的层次结构也只能有一个级别,只所以混淆是因为它也是一种维度,不过是特殊的维度。
MSDN的解释如下，"A measures dimension is the dimension that contains all of the measures in a cube. A measures dimension is a special type of dimension in which the members are typically aggregated (generally by sum or by count) based on the current member of each dimension attribute with which a specified measure exists"
仔细研究以后发现，其实此处的度量维度就是指所有的度量，换句话说度量被当成了一种特殊的维度，这个维度如果有层次结构的话，他的层次结构也只能有一个级别,只所以混淆是因为它也是一种维度,不过是特殊的维度。
http://www.cnblogs.com/anshangcun/archive/2007/10/30/943360.html
度量值组
度量值组 (Measure Group)“度量值组”是 SQL Server Analysis Services 中一个多维数据集的相关度量值集合（通常是来自同一事实数据表...
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Measures and Measure Groups
A measure represents a column that contains quantifiable data, usually numeric, that can be aggregated. A measure is generally mapped to a column in a fact table.
Attribute columns from dimension tables can be used to define measures, but such measures are typically semiadditive or nonadditive in terms of their aggregation behavior.
You can also define a measure as a calculated member by using a Multidimensional Expressions (MDX) to provide a calculated value for a measure based on other measures in the cube.
Measure Groups
In a cube, measures are grouped by their underlying fact tables into measure groups. Measure groups are used to associate dimensions with measures.
The fact table contains two basic types of columns: attribute columns and measure columns. Attribute columns are used to create foreign key relationships to dimension tables, so that the quantifiable data in the measure columns can be organized by the data contained in the dimension tables.Attribute columns are also used to define the granularity of a fact table and its measure group.
Granularity
Granularity refers to the level of detail supported by a fact table.
The granularity of a measure group can never be set finer than the lowest level of the dimension from which the measure group is viewed, but the granularity can be made coarser by using additional attributes.
Aggregate Functions
When a dimension is used to organize measures in a measure group, the measure is summarized along the hierarchies contained in that dimension. The summation behavior depends on the aggregate function specified for the measure.
Attribute columns from dimension tables can be used to define measures, but such measures are typically semiadditive or nonadditive in terms of their aggregation behavior.
You can also define a measure as a calculated member by using a Multidimensional Expressions (MDX) to provide a calculated value for a measure based on other measures in the cube.
Measure Groups
In a cube, measures are grouped by their underlying fact tables into measure groups. Measure groups are used to associate dimensions with measures.
The fact table contains two basic types of columns: attribute columns and measure columns. Attribute columns are used to create foreign key relationships to dimension tables, so that the quantifiable data in the measure columns can be organized by the data contained in the dimension tables.Attribute columns are also used to define the granularity of a fact table and its measure group.
Granularity
Granularity refers to the level of detail supported by a fact table.
The granularity of a measure group can never be set finer than the lowest level of the dimension from which the measure group is viewed, but the granularity can be made coarser by using additional attributes.
Aggregate Functions
When a dimension is used to organize measures in a measure group, the measure is summarized along the hierarchies contained in that dimension. The summation behavior depends on the aggregate function specified for the measure.
http://www.cnblogs.com/csgashine/articles/559377.html
SSAS几个名词
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