Command Query Responsibility Segregation

CQRS

Kind: pattern

Layer: Execution Core

Aliases: CQRS

Record: architecture:command-query-responsibility-segregation

Severity: contextual

Scope: application, data access

Canonical: Ontology

A design pattern that separates the model that handles commands from the model that answers queries.

Listed in Architecture principles, after Event Sourcing and before Domain Events.

Requires

• Command/Query Separation

Reinforces

• Scalability
• Event Sourcing

Enables

• Read/Write Model Optimization

Conflicts with

• Unified CRUD Model

In tension with

• Eventual Consistency

Tensions

• Command Query Responsibility Segregation (CQRS) / Eventual Consistency

Violated by

• Unified CRUD Model

Severity

• contextual

Category

• Event / Messaging / Asynchronous Architecture

Enabled by

• Event-Driven Architecture

Linked from

• Every record has a kind
• Event / Messaging / Asynchronous Architecture
• Scalability / Performance / Optimization
• Event Messaging Async
• Severity levels
• The resolutions