/working-with-dbt-mesh

Groups and Access Modifiers

Groups and access modifiers work together to organize models by team ownership and control which models can reference each other.

Groups

Groups represent domains of resources owned by a specific team. They make ownership explicit — when something breaks, you know who to contact.

Defining Groups

Groups can be defined in a standalone YAML file or alongside model definitions:

# models/_groups.yml (or any .yml file in your models directory)
groups:
  - name: finance
    owner:
      name: Firstname Lastname
      email: finance@jaffleshop.com
      slack: finance-data
      github: finance-data-team
  - name: product
    owner:
      email: product@jaffleshop.com
      github: product-data-team

Owner requirements: At least name or email is required. Other properties (slack, github) are optional.

Assigning Models to Groups

Three ways to assign a model to a group:

1. In model YAML (recommended for individual models):

models:
  - name: fct_orders
    config:
      group: finance

2. In dbt_project.yml (recommended for directory-level assignment):

# dbt_project.yml
models:
  my_project:
    marts:
      finance:
        +group: finance
      marketing:
        +group: marketing

3. In SQL config block:

-- models/marts/finance/fct_orders.sql
{{ config(group='finance') }}

select ...

What Can Be Grouped

Groups apply to: models, seeds, snapshots, tests, analyses, metrics, semantic models, and saved queries.

Access Modifiers

Access modifiers control which models can ref yours:

Configuring Access

Important: access is a config property and must be nested under config: in YAML property files. Placing it as a top-level model property breaks the Fusion engine. The same applies to group — always co-locate them under config:.

# ✅ CORRECT
models:
  - name: fct_orders
    config:
      group: finance
      access: public

# ❌ WRONG — breaks Fusion
models:
  - name: fct_orders
    access: public     # not under config:
    group: finance     # not under config:

In dbt_project.yml at the directory level, use the + prefix:

models:
  my_project:
    staging:
      +access: private
      +group: platform
    marts:
      +access: protected

Or in SQL:

{{ config(access='public', group='finance') }}

Access Rules

• Default access is protected — all models in a project can reference each other regardless of group
• private models trigger a DbtReferenceError if referenced from outside their group
• public models are the only models visible to other projects via cross-project ref()
• Ephemeral models cannot be public — attempting this causes a parsing error

Access and Contracts

Access and contracts are complementary:

Practical Example: Multi-Team Project

# models/_groups.yml
groups:
  - name: finance
    owner:
      email: finance-data@company.com
  - name: marketing
    owner:
      email: marketing-data@company.com

# models/marts/finance/_finance_models.yml
models:
  - name: fct_revenue
    config:
      group: finance
      access: public       # Other projects can ref this
      contract:
        enforced: true
    columns:
      - name: revenue_id
        data_type: varchar
      - name: amount
        data_type: numeric(38, 2)
      - name: recorded_at
        data_type: timestamp_ntz

  - name: int_revenue_daily
    config:
      group: finance
      access: private       # Only finance group can ref this

# models/marts/marketing/_marketing_models.yml
models:
  - name: fct_campaigns
    config:
      group: marketing
      access: protected     # Same project can ref, other projects cannot

In this setup:

• fct_revenue is available to anyone (public, contracted)
• int_revenue_daily is only available within the finance group
• fct_campaigns is available to all models in the same project but not to other projects
• If fct_campaigns tries to ref('int_revenue_daily'), dbt raises a DbtReferenceError

Best Practices

1. Start with private for new models and widen access only when there's a real consumer
2. Always pair public with a contract — a public model without a contract is a liability
3. Use directory-level group assignment in dbt_project.yml when your directory structure mirrors team ownership
4. Keep groups aligned with team structure — a group should map to a real team that can respond to issues
5. Don't create groups for one model — groups represent team boundaries, not individual model boundaries

Common Mistakes