Aggregation refers to the computation of a function across a defined set of facts.
Facts are raw numerical data pulled from the source, which may be of limited value on their own. Examples of facts might include:
- Revenue earned from a sale
- Cost of some item purchased
- Hours worked by one employee
- Number of items shipped in a delivery
Facts are stored with contextual data in a raw form in the datastore. To derive insights from fact data, you must aggregate facts into metrics.
For example, you might sum all of the sales revenue data (the Sales Revenue fact) for the entire country. Or you might slice this aggregation by a specific region of the country:
These aggregations, called metrics, are referenced by name in the What pane of your reports to deliver meaningful insights to your project's users. Metrics can also be referenced within the definitions of other metrics.
Use the following aggregations to form metrics:
For more information, see Platform Glossary.
Metrics contain other interesting features. In the previous simple example, the
WHERE clause includes information that defines the range of facts across which the sum is computed. You can also apply any of the following types of operations within a metric definition: