DBT Macros & Jinja Flashcards

Which dbt macro is used to generate a cross-database compatible date-trunc expression?

Answer: dbt.date_trunc()

`dbt.date_trunc(datepart, date)` is a built-in cross-database macro that adapts the date_trunc SQL function for each supported adapter.

What does the `var()` function do in a dbt model?

Answer: Reads a project variable defined in dbt_project.yml or passed via --vars

`{{ var('name', default) }}` reads variables from the `vars:` section of dbt_project.yml or those overridden at runtime with `--vars`.

How do you pass a runtime variable override when running dbt?

Answer: dbt run --vars '{key: value}'

The `--vars` flag accepts a YAML dictionary string that overrides project variables for the duration of the run.

What Jinja construct lets you loop over a list and generate repeated SQL fragments in dbt?

Answer: {% for item in list %} ... {% endfor %}

`{% for item in list %}...{% endfor %}` iterates over a list and renders the body for each element, enabling dynamic SQL generation.

What is the purpose of `adapter.dispatch()` in dbt macros?

Answer: Finds the correct macro implementation for the active database adapter

`adapter.dispatch()` enables polymorphism by resolving a macro to its adapter-specific implementation (e.g., Snowflake vs BigQuery).

Which built-in dbt macro returns a surrogate key hashed from one or more column expressions?

Answer: dbt_utils.generate_surrogate_key()

`dbt_utils.generate_surrogate_key([col1, col2])` concatenates and hashes the specified columns to produce a consistent surrogate key.