CQRS Pattern With MediatR

CQRS separates the write side and the read side of an application, either as a logical split in one database or as a physical split across two. The text ties this to MediatR by extending IRequest into ICommand and IQuery, then sending each request through ISender to its handler.

Reading notes

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• CQRS gives commands and queries their own models so writes and reads can be optimized independently.
• The split can be logical in one database or physical across two databases.
• The text lists complexity management, improved performance, scalability, flexibility, and security as benefits.
• CQS is described as a method-level principle, while CQRS is its architectural evolution.
• With multiple databases, CQRS introduces eventual consistency and the need to handle synchronization failures.
• MediatR is presented as a way to apply CQRS with IRequest, custom ICommand and IQuery abstractions, and ISender.
• On the write side, the text favors EF Core and a rich domain model.
• On the read side, it favors minimal indirection, such as Dapper with raw SQL, database views, or EF Core projections.
• The request pipeline can handle cross-cutting concerns, including validation through IPipelineBehavior.