What is the difference between Event Sourcing and Command Query Responsibility Segregation (CQRS)?

Event Sourcing and CQRS are related patterns, but they serve different purposes and are

often used together:

• Event Sourcing: Focuses on how state changes are stored and communicated. It

stores events instead of the current state of an entity. The events can be replayed to

Follow :

rebuild the state, ensuring that every state change is traceable and auditable.

• CQRS: Separates the command (write) and query (read) operations into distinct

models. In CQRS, the write model (or command) is responsible for modifying data,

and the read model (or query) is optimized for querying data. This separation allows

for optimizations in both reading and writing.

How they relate:

• Event Sourcing can serve as the write model in CQRS. Events are stored as part of

the write process.

• The read model in CQRS can be a materialized view (a denormalized

representation) that is optimized for querying, which may be updated asynchronously

based on the events.