A typical enterprise application can have three parts: frontend with some HTML, CSS, angular stuff; a server part that handles requests and does some business logic; and a database part that has tables for all the contexts we have in our application. If you need to add one new thing to a database or at server side, even if it is in a tiny and isolated part of the application, you have to deploy the whole application. It tends to cause downtime, which is not very acceptable in today's era.

In these kind of scenarios, microservice comes up with a solution. However, migrating monolith to microservices is not easy and includes lots of decisions and considerations. Here, we are mainly talking about migrating from a database model of monolithic architecture to microservices-based architecture. One can go with a big step and convert the whole monolith application into microservices. Another option is go step by step and find a piece of a data model that can be used as a separate data model without affecting much of the whole application's data model.

The main concern of migrating from a monolith database is confusion while extracting your microservice databases. There is no foolproof plan for this. There are patterns that help us understand what approach we can use to create our microservices data model. While breaking monolith to microservices, you know better which data mostly updates together, or you can take the help of domain experts too. Let's understand Domain-Driven Design better.