Polyglot persistence is all about using different databases for different business needs within a single distributed system. We already have different database products in the market each for a specific business need, for example:  RDBMS Relational databases are used for transactional needs (storing financial data, reporting requirements, etc.)  MongoDB Documented oriented databases are used for documents oriented needs (for e.g. Product Catalog). Documents are schema-free so changes in the schema can be accommodated into the application without much headache. Cassandra/Amazon DynamoDB Key-value pair based database (User activity tracking, Analytics, etc.). DynamoDB can store documents as well as key-value pairs. Redis In memory distributed database (user session tracking), its mostly used as a distributed cache among multiple microservices. Neo4j  Graph DB (social connections, recommendations, etc)  Benefits of Polyglot Persistence are manifold and can be harvested in both monolithic as well as microservices architecture. Any decent-sized product will have a variety of needs which may not be fulfilled by a single kind of database alone. For example, if there are no transactional needs for a particular microservice, then it's way better to use a key-value pair or document-oriented NoSql rather than using a transactional RDBMS database.  References: https://martinfowler.com/bliki/PolyglotPersistence.html