PR review workflows for dbt changes - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Key Step in PR Review Workflow for dbt Model Changes

In a typical PR review workflow for dbt model changes, which step ensures that the new or modified models do not break existing data transformations?

A Merging the PR directly without any checks

B Running dbt tests and validations on the changed models

C Deleting the existing models before merging

D Ignoring the PR and continuing development

💡 Hint

Think about how to verify that changes are safe before merging.

Running dbt tests and validations helps catch errors or issues introduced by changes, ensuring data integrity before merging.

❓ Predict Output

intermediate

Output of dbt run in PR Workflow

What is the expected output when running dbt run during a PR review for a model that has no syntax errors and passes all dependencies?

dbt

dbt run

A All models run successfully with status 'OK' and no errors

B Syntax errors reported and run aborted

C Partial models run with some failures

D No output is shown

💡 Hint

Consider what happens when dbt runs models without issues.

If the models have no syntax errors and dependencies are met, dbt run completes successfully with all models marked as 'OK'.

🔧 Debug

advanced

Identifying the Cause of a Failed dbt Test in PR Review

During a PR review, a dbt test fails with the error: unique key violation. What is the most likely cause?

A The test syntax is incorrect

B The dbt project configuration file is missing

C The database connection is lost

D The model contains duplicate values in a column that should be unique

💡 Hint

Think about what a unique key violation means in data.

A unique key violation means the data has duplicates in a column that is expected to have unique values, causing the test to fail.

🚀 Application

advanced

Best Practice for Handling Schema Changes in PR Workflow

When a PR includes schema changes like adding a new column to a dbt model, what is the best practice to ensure smooth deployment?

A Add the new column in the model and update tests and documentation accordingly before merging

B Merge the PR without updating tests or documentation

C Delete the old model and create a new one with the new schema

D Ignore schema changes and only update SQL logic

💡 Hint

Think about maintaining quality and clarity in your dbt project.

Updating tests and documentation ensures the new schema is validated and clearly understood, preventing issues after deployment.

❓ visualization

expert

Interpreting a dbt DAG Graph in PR Review

You see a DAG graph generated by dbt during a PR review. The graph shows a model with multiple upstream dependencies and several downstream models. What does this imply about the impact of changes to this model?

A Changes to this model only affect itself and no other models

B This model has no dependencies and is isolated

C Changes to this model can affect many other models both upstream and downstream

D The graph is incorrect and should be ignored

💡 Hint

Consider what upstream and downstream dependencies mean in a DAG.

A model with many upstream and downstream dependencies means changes can ripple through the project, affecting many models.