Dimension Table

A Dimension Table is a relational table that categorizes facts and measures.

• • …
• Counter-Example(s):
  • A Fact Table.
• See: Measure (Data Warehouse), Categorical Variable, Data Warehouse, Fact (Data Warehouse), Data Set, Data Element.

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References

2020

• (Wikipedia, 2020) ⇒ https://en.wikipedia.org/wiki/Dimension_(data_warehouse)#Dimension_table Retrieved:2020-2-28.
  • A dimension is a structure that categorizes facts and measures in order to enable users to answer business questions. Commonly used dimensions are people, products, place and time. . (Note: People and time sometimes are not modeled as dimensions.)

    In a data warehouse, dimensions provide structured labeling information to otherwise unordered numeric measures. The dimension is a data set composed of individual, non-overlapping data elements. The primary functions of dimensions are threefold: to provide filtering, grouping and labelling.

    These functions are often described as "slice and dice". A common data warehouse example involves sales as the measure, with customer and product as dimensions. In each sale a customer buys a product. The data can be sliced by removing all customers except for a group under study, and then diced by grouping by product.

    A dimensional data element is similar to a categorical variable in statistics.

    Typically dimensions in a data warehouse are organized internally into one or more hierarchies. "Date" is a common dimension, with several possible hierarchies:

    • "Days (are grouped into) Months (which are grouped into) Years",
    • "Days (are grouped into) Weeks (which are grouped into) Years"
    • "Days (are grouped into) Months (which are grouped into) Quarters (which are grouped into) Years"
    • etc.

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