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Impact Analysis

The core feature of DBT Column Lineage - understand the downstream effects of changing a column before you make the change.

Overview

Impact Analysis is the primary reason to use DBT Column Lineage. It helps you answer the critical question: "What happens if I change this column?"

Column-level lineage is the tool that enables this analysis. By tracking how data flows through your transformations at the column level, we can show you exactly what will be affected when you modify a column.

When you select a column in the Interactive Explorer, you can analyze its impact across your entire dbt project. This feature shows you:

  • Which models and columns depend on this column
  • Which transformations (SUM, CASE, etc.) use this column and may need review
  • Which dashboards and exposures will be impacted

How to Use

  1. Start the Interactive Explorer: 

    dbt-col-lineage --explore

  2. Select a model and column from the sidebar

  3. Load the lineage graph

  4. Click "Analyze Impact" in the card that appears on the graph

  5. Review the impact analysis panel that opens on the right

Understanding the Results

The impact analysis categorizes columns into:

  • Requires Review: Columns with transformations (derived columns) that may break if the source column changes
  • Pass-through Columns: Direct references that will automatically propagate changes
  • Affected Models: All models in the dependency chain
  • Affected Exposures: Dashboards and reports that may be impacted

Impact Analysis Screenshot Impact Analysis panel showing column dependencies and transformations

Use Cases

Before modifying a column: - Understand which transformations depend on it - Identify which dashboards need updates - Plan your change strategy

During refactoring: - Track the blast radius of schema changes - Prioritize which models to update first - Ensure no downstream dependencies are missed