MSA Data mgmt patterns -> Command Query Responsibility Segregation (CQRS)

Problem

Once we implement database-per-service, there is a requirement to query, which requires joint data from multiple services — it's not possible. Then, how do we implement queries in microservice architecture?

 Solution

 CQRS suggests splitting the application into two parts — the command side and the query side.

• The command side handles the Create, Update, and Delete requests.
• The query side handles the query part by using the materialized views.

The event sourcing pattern is generally used along with it to create events for any data change. Materialized views are kept updated by subscribing to the stream of events.