# A dbt project's CI rebuilds every model on every PR Canonical URL: Domain: Pipeline Design ยท Difficulty: medium ## Problem A dbt project's CI rebuilds every model on every PR. Engineers stopped running CI locally because it takes 45 minutes; they push and watch it fail in GitHub. The section names four CI test layers (code, logic, schema/contracts, integration) and the slim-CI optimization: build only the models that changed plus their downstream descendants, against a deferred dev warehouse, with teardown after the PR closes. Design the test plan by replacing the CI step with a slim-CI runner whose name states the four test layers, the changed-models-plus-descendants selector, the deferred dev warehouse, and the teardown. ## Related - [All practice problems](https://datadriven.io/problems) - [Mock interview mode](https://datadriven.io/interview/a-dbt-projects-ci-rebuilds-every-model-on-every-pr-enginee-6a564ada) - [System Design Interview Questions](https://datadriven.io/data-engineering-system-design) - [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep) - [Daily Challenge](https://datadriven.io/daily) --- Source: DataDriven (https://datadriven.io). 100% free data engineering interview prep. Live code execution against Postgres 16, Python 3.11, and Spark sandboxes. No paywall, no premium tier, no signup gate.