Azure Cosmos DB is the globally distributed, multi-model database service for building planet scale apps. You can easily build globally-distributed applications without the hassle of complex, multiple-datacenter configurations. Cosmos DB automatically replicates all of your data to any number of regions of your choice, for fast, responsive access. Cosmos DB guarantees 99.99% high availability.
Only Cosmos DB allows you to use key-value, graph, and document data in one service.
One of the APIs Azure Cosmos DB supports is the SQL (DocumentDB) API.
https://azure.microsoft.com/en-in/blog/dear-documentdb-customers-welcome-to-azure-cosmos-db/ is a good link to read further.
To build always-on, scalable, distributed applications in azure from your development machine, you need to ensure right tools are already installed.
This blog is to install tools for VS 2017.
While installing or modifying VS 2017 on your development machine ensure option ‘Azure development’ is checked on.
Apart from this you need Microsoft Azure Service Fabric SDK on your machine. The SDK gets installed using Web installer 5.0. The link for SDK is:
Visual studio is now ready to allow you create service fabric applications.
Choose the service you want to create: