In data warehousing, a fact table consists of the measurements, metrics or facts of a business process. It is located at the center of a star schema or a snowflake schema surrounded by dimension tables. Where multiple fact tables are used, these are arranged as a fact constellation schema.
Fact tables provide the (usually) additive values that act as independent variables by which dimensional attributes are analyzed. Fact tables are often defined by their grain. The grain of a fact table represents the most atomic level by which the facts may be defined. The grain of a SALES fact table might be stated as "Sales volume by Day by Product by Store". Each record in this fact table is therefore uniquely defined by a day, product and store. Other dimensions might be members of this fact table (such as location/region) but these add nothing to the uniqueness of the fact records. These "affiliate dimensions" allow for additional slices of the independent facts but generally provide insights at a higher level of aggregation (a region contains many stores).
Read more about Fact Table: Example, Measure Types, Types of Fact Tables, Steps in Designing A Fact Table
Famous quotes containing the words fact and/or table:
“What preoccupies us, then, is not God as a fact of nature, but as a fabrication useful for a God-fearing society. God himself becomes not a power but an image.”
—Daniel J. Boorstin (b. 1914)
“Remember thee?
Ay, thou poor ghost, whiles memory holds a seat
In this distracted globe. Remember thee?
Yea, from the table of my memory
I’ll wipe away all trivial fond records,
All saws of books, all forms, all pressures past
That youth and observation copied there,
And thy commandment all alone shall live
Within the book and volume of my brain,”
—William Shakespeare (1564–1616)