DBT DBT Snapshots & Incremental Models 2

Question 1

What value does dbt store in `dbt_valid_to` for the currently active snapshot row?

Accepted Answer

NULL

Answer

An open-ended (current) snapshot row has `dbt_valid_to = NULL`, indicating the record is still active.

Question 2

Which materialization causes dbt to append only new or changed rows instead of rebuilding the whole table?

Accepted Answer

incremental

Answer

The `incremental` materialization adds or updates only rows that are new since the last run, making large-table processing efficient.

Question 3

What block in an incremental model filters the source data to only new records?

Accepted Answer

{% if is_incremental() %}

Answer

`{% if is_incremental() %}` is a dbt Jinja macro that returns true only when the model is running in incremental mode (not full-refresh), allowing you to add a WHERE clause.

Question 4

What does `dbt run --full-refresh` do to an incremental model?

Accepted Answer

Rebuilds the table from scratch, ignoring the existing data

Answer

`--full-refresh` drops and recreates an incremental model's table from the ground up, equivalent to the initial build.

Question 5

Which incremental `strategy` is recommended for Snowflake and BigQuery to efficiently update existing rows?

Accepted Answer

merge

Answer

The `merge` strategy uses a SQL MERGE statement to upsert rows, updating existing records and inserting new ones in a single pass.

DBT - Certified Data Build Tool Developer Practice Test

DBT - Certified Data Build Tool Developer Practice Test

DBT DBT Snapshots & Incremental Models 2