Early-arriving fact

In the Data Warehouse practice of ETL, an early fact or early-arriving fact [1] denotes the detection of a dimensional natural key during fact table source loading, prior to the assignment of a corresponding primary key or surrogate key in the dimension table. Hence, the fact which cites the dimension arrives early, relative to the definition of the dimension value.

Procedurally, an early fact can be treated as:

• an error, on the presumption that the dimensional attribute values should have been collected before fact source loading.
• a valid fact, whose collection pauses whilst the missing dimensional attribute value itself is collected.
• a valid fact, where a primary key value is generated on the dimension with no attributes (stub / dummy row), the fact completes processing, and the dimension attributes are populated (overwritten) later in the load processing on the new row.