Column descriptions in dbt - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of column descriptions in dbt

What is the main purpose of adding column descriptions in a dbt model?

A To provide clear explanations of what each column represents for better understanding and documentation.

B To change the data type of the column during model compilation.

C To automatically generate SQL queries for data transformation.

D To enforce data validation rules on the column values.

💡 Hint

Think about why documentation is important in data projects.

Column descriptions help users and team members understand the meaning and purpose of each column, improving collaboration and data quality.

❓ Predict Output

intermediate

Output of dbt column description YAML snippet

Given the following dbt schema YAML snippet, what will be the description of the customer_id column in the generated documentation?

dbt

models:
  - name: orders
    columns:
      - name: customer_id
        description: "Unique identifier for each customer"

A "Primary key for orders table"

B "Unique identifier for each customer"

C "Date when the order was placed"

D "Total amount of the order"

💡 Hint

Look at the description field under the customer_id column.

The description field directly defines the text shown in documentation for that column.

❓ data_output

advanced

Effect of missing column descriptions in dbt docs

What will be the output in the dbt documentation site for a column that has no description provided in the schema YAML?

A The data type of the column shown instead of description.

B An error message preventing documentation generation.

C The column name repeated as the description automatically.

D "No description provided" or blank space under the column description section.

💡 Hint

Consider how dbt handles optional documentation fields.

If no description is provided, dbt docs shows an empty or placeholder text indicating no description is available.

🔧 Debug

advanced

Identify the error in this dbt column description YAML

Which option contains a syntax error that will cause dbt to fail when parsing this column description YAML?

dbt

models:
  - name: sales
    columns:
      - name: sale_date
        description: "Date of the sale"
      - name: amount
        description "Total sale amount"

A Incorrect indentation for the 'sale_date' column description.

B Using double quotes instead of single quotes for descriptions.

C Missing colon after 'description' for the 'amount' column.

D Missing dash before the 'amount' column name.

💡 Hint

Look carefully at the line defining the description for the 'amount' column.

YAML requires a colon after keys. Missing colon after 'description' causes a syntax error.

🚀 Application

expert

Using column descriptions to improve data quality communication

You want to use column descriptions in dbt to communicate data quality expectations for a status column that only accepts values 'active', 'inactive', or 'pending'. Which description best achieves this goal?

A "Status of the user account; valid values are 'active', 'inactive', or 'pending'."

B "User account status."

C "Contains various status codes."

D "Indicates if the user is logged in or not."

💡 Hint

Think about how to clearly communicate allowed values in documentation.

Option A clearly states the valid values, helping users understand data quality rules.