Model Selection¶

When working with a project that has many models, you often want to run only a subset. smelt provides --select and --exclude flags to control which models are included in a run.

These flags are available on smelt run, smelt build, and smelt explain.

Selection syntax¶

By name¶

Select a single model by its name:

smelt run --select daily_revenue

By tag¶

Select all models with a given tag:

smelt run --select tag:revenue

Tags are assigned in smelt.yml or in YAML frontmatter:

# smelt.yml
models:
  daily_revenue:
    tags: [revenue, daily]

---
tags: [revenue, daily]
---
SELECT ...

Include upstream dependencies¶

Prefix with + to include the selected model(s) and all their upstream dependencies:

smelt run --select +daily_revenue
smelt run --select +tag:revenue

This ensures that every model daily_revenue depends on is also run, in the correct order.

Include downstream dependents¶

Suffix with + to include the selected model(s) and everything that depends on them:

smelt run --select daily_revenue+
smelt run --select tag:staging+

Include both upstream and downstream¶

Combine the prefix and suffix:

smelt run --select +daily_revenue+

This selects daily_revenue, all its upstream dependencies, and all its downstream dependents.

Multiple selectors¶

The --select flag is repeatable. All selectors are combined (union):

smelt run --select daily_revenue --select user_activity

Short form with -s:

smelt run -s daily_revenue -s user_activity

Excluding models¶

The --exclude flag uses the same syntax as --select but removes models from the selection:

smelt run --exclude tag:expensive
smelt run --exclude staging_legacy

Exclusions are applied after selections. If you use --select and --exclude together, smelt first builds the selected set, then removes the excluded models.

Practical examples¶

Run a single model¶

smelt run --select daily_revenue

Run a model and all its dependencies¶

smelt run --select +daily_revenue

Run everything downstream of staging¶

smelt run --select tag:staging+

Run everything except expensive models¶

smelt run --exclude tag:expensive

Run a specific model with dependencies, excluding one branch¶

smelt run --select +daily_revenue --exclude user_activity

Explain selected models¶

smelt explain --select +daily_revenue
smelt explain --select tag:revenue --json

How selection works¶

If no --select flags are provided, all models are included.
Each --select flag adds models to the set. The + prefix/suffix expands the set by walking the dependency graph.
Each --exclude flag removes models from the set, using the same expansion rules.
The final set is executed in topological order (dependencies first).

Tip

During development, use --select +model_name to run just the model you are working on along with its dependencies. This is much faster than running the entire project.