impact

dbt-forge impact shows which models are affected when you change an upstream model. Use it to understand blast radius before merging changes and to communicate risk in pull requests.

Command

dbt-forge impact <MODEL> [--diff] [--base REF] [--pr]

What it does

The command builds a dependency graph from ref() and source() calls in your SQL, then computes the downstream impact of one or more changed models. It shows:

• A tree of all affected downstream models, colored by depth
• Blast radius: how many models are impacted as a percentage of the total project
• Direct vs transitive impact counts
• Untested impacted models (models without any tests defined)

Arguments

MODEL

The model name to analyze. Shows all downstream dependents as a Rich tree.

dbt-forge impact stg_orders

Options

--diff

Auto-detect changed models from git diff instead of specifying a model name. Compares the current branch against the base ref.

dbt-forge impact --diff
dbt-forge impact --diff --base develop

--base

Base git ref for --diff comparison. Defaults to main.

dbt-forge impact --diff --base origin/main

--pr

Output markdown formatted for pull request descriptions. Includes a summary table with blast radius, impacted model counts, and untested model warnings.

dbt-forge impact stg_orders --pr
dbt-forge impact --diff --pr

Output

Tree view (default)

stg_orders
├── fct_orders (direct)
│   └── rpt_revenue (transitive)
└── fct_order_items (direct)

Blast radius: 66.7% (2 of 3 models impacted)
Direct: 2  Transitive: 1  Untested: 1

PR markdown (--pr)

## Impact Analysis

**Changed models:** `stg_orders`

| Metric | Value |
|--------|-------|
| Total impacted | 2 |
| Direct | 1 |
| Transitive | 1 |
| Blast radius | 66.7% |

### Untested impacted models
- `rpt_revenue`

Behavior and limits

• Must run from inside an existing dbt project (walks up to find dbt_project.yml).
• Builds the graph from ref() and source() regex patterns in SQL files.
• The --diff flag uses git diff --name-only {base}...HEAD -- models/ to detect changed .sql files.
• Models not found in the graph (typos, non-existent models) produce an error message without crashing.
• Untested models are detected by scanning YAML files for data_tests: entries.
• If no model is specified and --diff is not set, the command prints a usage error.