wshobson/dbt-transformation-patterns

dbt Transformation Patterns

Production-ready patterns for dbt (data build tool) including model organization, testing strategies, documentation, and incremental processing.

When to Use This Skill

• Building data transformation pipelines with dbt
• Organizing models into staging, intermediate, and marts layers
• Implementing data quality tests
• Creating incremental models for large datasets
• Documenting data models and lineage
• Setting up dbt project structure

Core Concepts

1. Model Layers (Medallion Architecture)

sources/          Raw data definitions
    ↓
staging/          1:1 with source, light cleaning
    ↓
intermediate/     Business logic, joins, aggregations
    ↓
marts/            Final analytics tables

2. Naming Conventions

| Layer | Prefix | Example | | ------------ | -------------- | ----------------------------- | | Staging | stg_ | stg_stripe__payments | | Intermediate | int_ | int_payments_pivoted | | Marts | dim_, fct_ | dim_customers, fct_orders |

Quick Start

# dbt_project.yml
name: "analytics"
version: "1.0.0"
profile: "analytics"

model-paths: ["models"]
analysis-paths: ["analyses"]
test-paths: ["tests"]
seed-paths: ["seeds"]
macro-paths: ["macros"]

vars:
  start_date: "2020-01-01"

models:
  analytics:
    staging:
      +materialized: view
      +schema: staging
    intermediate:
      +materialized: ephemeral
    marts:
      +materialized: table
      +schema: analytics

# Project structure
models/
├── staging/
│   ├── stripe/
│   │   ├── _stripe__sources.yml
│   │   ├── _stripe__models.yml
│   │   ├── stg_stripe__customers.sql
│   │   └── stg_stripe__payments.sql
│   └── shopify/
│       ├── _shopify__sources.yml
│       └── stg_shopify__orders.sql
├── intermediate/
│   └── finance/
│       └── int_payments_pivoted.sql
└── marts/
    ├── core/
    │   ├── _core__models.yml
    │   ├── dim_customers.sql
    │   └── fct_orders.sql
    └── finance/
        └── fct_revenue.sql

Detailed patterns and worked examples

Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.

Best Practices

Do's

• Use staging layer - Clean data once, use everywhere
• Test aggressively - Not null, unique, relationships
• Document everything - Column descriptions, model descriptions
• Use incremental - For tables > 1M rows
• Version control - dbt project in Git

Don'ts

• Don't skip staging - Raw → mart is tech debt
• Don't hardcode dates - Use {{ var('start_date') }}
• Don't repeat logic - Extract to macros
• Don't test in prod - Use dev target
• Don't ignore freshness - Monitor source data