dbt-transformation-patterns

SKILL.md 节选

# 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

```yaml
# 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
```

## Patterns

### Pattern 1: Source Definitions

```yaml
# models/staging/stripe/_stripe__sources.yml
version: 2

sources:
  - name: stripe
    description: Raw Stripe data loaded via Fivetran
    database: raw
    schema: stripe
    loader: fivetran
    loaded_at_field: _fivetran_synced
    freshness:
      warn_after: {count: 12, period: hour}
      error_after: {count: 24, period: hour}
    tables:
      - name: customers
        description: Stripe customer records
        columns:
          - name: id
            description: Primary key
            tests:
              - unique
              - not_null
          - name: email
            description: Customer email
          - name: created
            description: Account creation timestamp

      - name: payments
        description: Stripe payment transactions
        columns:
          - name: id
            tests:
              - unique
              - not_null
          - name: customer_id
            tests:
              - not_null
              - relationships:
                  to: source('stripe', 'customers')
                  field: id
```

### Pattern 2: Staging Models

```sql
-- models/staging/stripe/stg_stripe__customers.sql
with source as (
    select * from {{ source('stripe', 'customers') }}
),

renamed as (
    select
        -- ids
        id as customer_id,

        -- strings
        lower(email) as email,
        name as customer_name,

        -- timestamps
        created as created_at,

        -- metadata
        _fivetran_synced as _loaded_at

    from source
)

select * from renamed
```

```sql
-- models/staging/stripe/stg_stripe__payments.sql
{{
    config(
        materialized='incremental',
        unique_key='payment_id',
        on_schema_change='append_new_columns'
    )
}}

with source as (
    select * from {{ source('stripe', 'payments') }}

    {% if is_incremental() %}
    where _fivetran_synced > (select max(_loaded_at) from {{ this }})

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