Data Modeling & Transformation Flashcards

What is the purpose of a dbt snapshot?

Answer: To record changes to mutable source rows over time (type-2 SCD)

Snapshots capture historical versions of rows with valid-from and valid-to columns.

Which snapshot strategy compares an updated_at column to detect changed rows?

Answer: timestamp

The timestamp strategy relies on an updated_at column and is the recommended one.

Which columns does dbt add to snapshot tables to track validity?

Answer: dbt_valid_from and dbt_valid_to

Snapshots add dbt_valid_from, dbt_valid_to, dbt_scd_id, and dbt_updated_at.

Which command loads CSV files from the seeds directory into the warehouse?

Answer: dbt seed

dbt seed loads CSV files as tables, suited to small static reference data.

Which is the best use case for a seed file?

Answer: A small, rarely changing mapping such as country codes

Seeds are for small static lookups version-controlled with the project.

What does `dbt build` do compared with `dbt run`?

Answer: Runs models, seeds, snapshots, and tests in DAG order

build executes seeds, models, snapshots, and tests together, in dependency order.

A model's tests fail during `dbt build`. What happens to its downstream models by default?

Answer: They are skipped

By default, downstream nodes are skipped when an upstream test or model fails.