Today, most large companies are using a variety of different data storage technologies for different kinds of data. A lot of companies still use relational databases to store some data, but the persistence needs of applications are evolving from predominantly relational to a mixture of data sources. Polyglot persistence is commonly used to define this hybrid approach. Increasingly, architects are approaching the data storage problem by first figuring out how they want to manipulate the data, and then choosing the appropriate technology to fit their needs. What polyglot persistence boils down to is choice – the ability to leverage multiple data storages, depending on your use cases.
Polyglot Persistence google