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How our team solved a DBT Dependency Challenge in a Data Project

In the world of data project management, unexpected challenges often arise, particularly when dealing with complex modeling and dependencies.

Here at LoopStudio, we recently encountered a unique problem while working on a project related to DBT (Data Build Tool) that isn’t widely discussed in documentation or courses.

This issue might resonate with many working on #data-projects, so I wanted to share our experience and solution.

The Challenge

solving dbt

In many scenarios, data models are built based on others. For example, a stg_customer model might lead to the creation of a dim_customer model.

But what happens when dim_customer has a Foreign Key (FK) dependency on dim_address, and dim_customer can only be created after a record in dim_address has been inserted or created?

DBT doesn’t inherently guarantee or define the order of model creation. Beyond using ref, which we typically employ to build one model based on another, there’s a complexity when a model isn’t built on another but is instead simply related by a constraint.

The Solution

To address this, we can use depends_on to enforce dependencies. This ensures that dim_customer depends on dim_address, meaning dim_customer will only execute after dim_address has finished executing.

This approach effectively resolves the issue of managing dependencies between models that aren’t directly built from one another but are instead linked by a constraint.

Visualizing the Solution with DBT Docs:

With dbt docs, we can visualize how our Directed Acyclic Graph (DAG) is structured. As shown in the documentation, there are clear relationships not only between the sources and the marts but also among the marts themselves.

Conclusion

This case study highlights an important aspect of working with DBT in data projects. Understanding and manipulating the dependencies can be crucial for the successful execution of complex data models.

Sharing these insights contributes to the broader community’s knowledge and helps in tackling similar challenges.