Monday, October 05, 2015

What is measure group, measure?

A simple MeasureGroup object is composed of: basic information, measures, dimensions, and partitions. Basic information includes the name of the measure group, the type of measures, the storage mode, the processing mode, and others. Measures are the actual set of measures that compose the measure group. For each measure there is a definition for the aggregate function, the formatting attribute, the data item source, and others. Dimensions are a subset of cube dimensions that will be used to create the processed measure group. Partitions are the collection of physical splits of the processed measure group.
In a cube, measures are grouped by their underlying fact tables into measure groups. Measure groups are used to associate dimensions with measures. Measure groups are also used for measures that have distinct count as their aggregation behavior. Placing each distinct count measure into its own measure group optimizes aggregation processing.
The following diagram represents the FactSalesQuota fact table and the two dimension tables associated with it, DimTime and DimEmployee.
FactSalesQuota table with two dimension tablesThe FactSalesQuota fact table defines the Sales Quotas measure group of the Adventure Works cube, and the DimTime and DimEmployee dimension tables define the Time and Employee dimensions in the Adventure Works DW sample Analysis Services project.
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. Measure columns define the measures contained by a measure group. In the FactSalesQuota fact table, the SalesAmountQuota column is used to define the Sales Amount Quota measure. This measure is contained by the Sales Quotas measure group, and is organized by the Time and Employee dimensions.

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