DBT Snapshots & Incremental Models Flashcards

What is the primary purpose of a dbt snapshot?

Answer: To capture and track slowly changing dimension (SCD) history in a source table

dbt snapshots implement Type 2 SCD logic, appending new rows when source data changes so you can query historical states.

Which directory stores dbt snapshot files by default?

Answer: snapshots/

Snapshot `.sql` files are placed in the top-level `snapshots/` directory of a dbt project.

What command runs all dbt snapshots?

Answer: dbt snapshot

`dbt snapshot` executes all snapshot files, applying the configured strategy to detect and record changes.

Which snapshot strategy compares a hash of all specified columns to detect row changes?

Answer: check

The `check` strategy hashes the values of listed columns and records a new snapshot row when the hash changes, useful when no reliable updated_at column exists.

Which snapshot strategy relies on an `updated_at` timestamp column to detect changes?

Answer: timestamp

The `timestamp` strategy compares the `updated_at` value between runs and creates new snapshot rows for records with a newer timestamp.

What column does dbt automatically add to a snapshot table to mark the time a record became current?

Answer: dbt_valid_from

`dbt_valid_from` is automatically populated with the timestamp when a snapshot row became the current version of the record.