Free DBT Data Modeling & Transformation Questions and Answers

Question 1

In dbt, what is a 'model' primarily used for?

Accepted Answer

Transform data using SQL

Answer

In dbt, a 'model' is primarily a SQL file that defines a specific data transformation. These models take raw data from source tables and apply SQL logic to clean, combine, aggregate, or reshape it into a more usable format. They are the core building blocks for creating a structured and transformed data layer in your data warehouse.

Question 2

What type of dbt materialization creates a new physical table in the warehouse each time it runs?

Accepted Answer

Table

Answer

The 'table' materialization in dbt creates a new physical table in your data warehouse every time the model is run. This means that the entire table is rebuilt from scratch with the latest data, replacing any existing version. While simple, it can be resource-intensive for very large datasets as it involves a full refresh each time.

Question 3

Which materialization type is used in dbt to improve performance by only updating new or changed records?

Accepted Answer

Incremental

Answer

The 'incremental' materialization type in dbt is designed to improve performance by only processing new or changed records since the last run. Instead of rebuilding the entire table, dbt intelligently inserts or updates only the relevant rows. This significantly reduces query times and computational resources, making it ideal for large, frequently updated datasets.

Question 4

What does 'ref()' function do in dbt models?

Accepted Answer

References another dbt model

Answer

The `ref()` function in dbt models is used to reference other dbt models or seeds within your project. It automatically creates a dependency between the models, ensuring that dbt builds them in the correct order. This function abstracts away the underlying table names, making your SQL more portable and readable.

Question 5

Which dbt file is responsible for describing the structure and relationships of data models?

Accepted Answer

schema.yml

Answer

The `schema.yml` file in dbt is crucial for documenting and testing your data models. It allows you to define descriptions for models and their columns, making your data catalog understandable. Additionally, you can specify data tests within this file to ensure data quality, such as checking for uniqueness or non-null values.

DBT - Certified Data Build Tool Developer Practice Test

DBT - Certified Data Build Tool Developer Practice Test

Free DBT Data Modeling & Transformation Questions and Answers