In most cases, a technical team prefers a database-per-service pattern to benefit from its loosely coupled services. With the recent advancement in database technologies, there are multiple flavors of data storage solutions available. Each performs the best for its targeted use cases.

For example, if your microservice needs the flexibility of a schemaless, document-like storage solution, you can choose a document store like MongoDB. If your microservice needs to establish a connection between millions or billions of users or entities, you can use a Graph store like Neo4j.

The point is that you now have a wide variety of database options to meet your business needs. These options perform well for the use case of your microservice — which is exactly why you need polyglot persistence.

Polyglot persistence involves using specialized database solutions when developing microservices, so each microservice can use a different type of database than the one used by another microservice.