Skip to main content

​
Overview

Views represent logical data models that define how to access and interpret data. They encapsulate the business logic needed to transform raw tables into meaningful business concepts. A view defines:
  • How to access data (table or custom SQL)
  • What entities exist in the data
  • Available dimensions (attributes)
  • Available measures (metrics and aggregations)

​
Basic View Structure

Create a file with the .view.yml extension in your semantics/views/ directory:
semantics/views/orders.view.yml
name: orders
description: "Order transactions and related data"
datasource: "local"
table: "orders.csv"

entities:
  - name: order
    type: primary
    description: "Individual order transaction"
    key: order_id

  - name: customer
    type: foreign
    description: "Customer who placed the order"
    key: customer_id

dimensions:
  - name: order_id
    type: number
    description: "Unique order identifier"
    expr: id

  - name: order_date
    type: date
    description: "Date when order was placed"
    expr: order_date

  - name: order_status
    type: string
    description: "Current status of the order"
    expr: status
    samples: ["pending", "shipped", "delivered", "cancelled"]

  - name: total_amount
    type: number
    description: "Total order amount"
    expr: total_amount

measures:
  - name: total_orders
    type: count
    description: "Total number of orders"

  - name: total_revenue
    type: sum
    description: "Total revenue from all orders"
    expr: total_amount

  - name: avg_order_value
    type: average
    description: "Average order value"
    expr: total_amount

​
View Properties

PropertyTypeRequiredDescription
namestringYesUnique identifier for the view
descriptionstringYesHuman-readable description of what this view represents
datasourcestringYesName of the datasource to use
tablestringConditionalDatabase table reference (required if sql not specified)
sqlstringConditionalCustom SQL query (required if table not specified)
entitiesarrayYesList of entities in this view
dimensionsarrayYesList of dimensions (attributes)
measuresarrayNoList of measures (aggregations)

​
SQL-Based Views

For complex transformations, use custom SQL instead of a direct table reference:
semantics/views/customer_metrics.view.yml
name: customer_metrics
description: "Aggregated customer metrics and segmentation"
datasource: "analytics"
sql: |
  SELECT 
    customer_id,
    COUNT(DISTINCT order_id) as total_orders,
    SUM(order_amount) as lifetime_value,
    MAX(order_date) as last_order_date,
    MIN(order_date) as first_order_date,
    CASE 
      WHEN SUM(order_amount) >= 1000 THEN 'High Value'
      WHEN SUM(order_amount) >= 500 THEN 'Medium Value'
      ELSE 'Low Value'
    END as value_segment
  FROM orders
  GROUP BY customer_id

entities:
  - name: customer
    type: primary
    description: "Customer entity with aggregated metrics"
    key: customer_id

dimensions:
  - name: customer_id
    type: number
    description: "Customer identifier"
    expr: customer_id

  - name: total_orders
    type: number
    description: "Number of orders placed by customer"
    expr: total_orders

  - name: value_segment
    type: string
    description: "Customer value segmentation"
    expr: value_segment
    samples: ["High Value", "Medium Value", "Low Value"]

measures:
  - name: total_customers
    type: count
    description: "Total number of customers"

  - name: avg_lifetime_value
    type: average
    description: "Average customer lifetime value"
    expr: lifetime_value

​
Best Practices

​
Naming

  • Use lowercase, descriptive names (e.g., orders, customer_metrics)
  • Keep names concise but clear
  • Avoid technical prefixes like tbl_ or view_

​
Structure

  • Keep views focused on a single primary entity
  • Use foreign entities to establish relationships between views
  • Organize related views in the same directory

​
Performance

  • Use table references when possible instead of complex SQL
  • Pre-aggregate data in SQL-based views when appropriate
  • Index the key columns referenced in entity definitions

​
Documentation

  • Always provide clear descriptions
  • Include sample values for important dimensions
  • Document any business rules or calculations

Entities

Define entities and relationships

Dimensions

Add dimensions to your views

Measures

Define measures and metrics

Overview

Back to semantic layer overview