Fact table

A fact table is a data warehousing concept. It consists of the measurements, metrics or facts of a business process. It is often located at the centre of a star schema, surrounded by dimension tables.

Example

Now if the business process is say SALES, then the fact table will typically contain values representing both raw facts and aggregations such as:

• $12,000, being "sales for New York store for 15-Jan-2005"
• $34,000, being "sales for Los Angeles store for 15-Jan-2005"
• $22,000, being "sales for New York store for 15-Jan-2005"
• $40,000, being "sales for Los Angeles store for 16-Jan-2005"
• $21,000, being "average daily sales for Los Angeles Store for Jan-2005"
• $35,000, being "average daily sales for Los Angeles Store for Feb-2005"
• $33,000, being "average daily sales for Los Angeles Store for year 2005"

"average monthly sales" is a measurement which is stored in the fact table. The fact table also contains foreign keys from the dimension tables, where time series (e.g. dates) and other dimensions (e.g. store location, salesman, product) are stored.