Add sources to your DAG

Define sources in .yml files nested under a sources: key to name and describe the data loaded into your warehouse by Extract and Load tools. Selecting from source tables in models with the {{ source() }} function helps define lineage, test assumptions about source data, and calculate freshness; dbt compiles the reference to the full table name and creates a dependency between the model and the source table. By default, schema will be the same as name; add schema only if you want a source name that differs from the existing schema. You can also add data tests to sources and descriptions that render as part of your documentation site, familiar concepts if you have already tested and documented models. Scope: dbt. Reviewed October 4, 2026.