Azure Cosmos DB

Microsoft aims to help us better manage our data with Microsoft’s globally distributed multi-model database service like Azure Cosmos DB which transparently scales and replicates your data wherever our users are. We can quickly create and query document, key/value, and graph databases, all of which benefit from the global distribution and horizontal scale capabilities at the core of Azure Cosmos DB.

Azure Cosmos DB provides native support for NoSQL choices, offers multiple well-defined consistency models, and guarantees single-digit-millisecond latencies at the 99th percentile, and guarantees high availability with multi-homing capabilities and low latencies anywhere in the world.

Multiple API and data model- Graphs, documents, columnar, key-value are all natively supported because of the ARS (atoms, records and sequences) design that Cosmos DB is built on. Microsoft team has been exposed the APIs for a subset of models right now (DocumentDB, MongoDB, Table, and Graph APIs) and we are working to expose other APIs in a similar way –

1. SQL API - Azure Cosmos DB natively supports document data model with familiar SQL API. 
2. MongoDB - A MongoDB database service built on top of Cosmos DB. Compatible with existing MongoDB libraries, drivers, tools and applications.
3. Azure Table API - Azure Cosmos DB offers native support for key-value pairs data with Azure Table API
4. Graph API - Azure Cosmos DB offers native support for graphs with Apache Gremlin API.

Cosmos DB has a schema agnostic indexing engine capable of automatically indexing all the data it ingests without requiring any schema or secondary indexes from the developer. The engine relies on a set of logical index layouts (inverted, columnar, tree) which decouple the storage layout from the index and query processing subsystems.

Key capabilities - As a globally distributed database service, Azure Cosmos DB provides the following capabilities to help you build scalable, highly responsive applications:

Feature	Description
Turnkey global distribution	Established globally distributed database system driven by the cloud-computing power of Azure. Data can be automatically replicated in Azure data centers around the world.
Multi-model and multi-API	Customers can use key-value, graph, and document data without worrying about schema or index management. Data is automatically indexed, which allows customers to access their data with the API of their choice including SQL, JavaScript, Gremlin, MongoDB, and Azure Table Storage.
Limitless elastic scale around the globe	Customers can independently scale storage and throughput. Azure Cosmos DB allows you to independently and elastically scale storage and throughput at anytime, anywhere across the globe, making it a perfect ally for your server less applications.
Multiple, well-defined consistency choices	Azure Cosmos DB offers five well-defined consistency levels—strong, bounded staleness, consistent-prefix, session, and eventual—for an intuitive programming model with low latency and high availability for your planet-scale app.
Guaranteed low latency at 99th percentile	Serve read and write requests from the nearest region while simultaneously distributing data across the globe. With its latch-free and write optimized database engine, Azure Cosmos DB guarantees less than 10-ms latencies on reads and less than 15-ms latencies on (indexed) writes at the 99th percentile.
Industry-leading, enterprise-grade SLAs	Offered service level agreements (SLAs) include 99.99% high availability, with latency at the 99th percentile.

DocumentDB API supports cross-document transactions expressed as JavaScript stored procedures and triggers. Transactions are scoped to a single partition within each collection and executed with ACID semantics as all or nothing isolated from other concurrently executing code and user requests. If exceptions are thrown through the server-side execution of JavaScript application code, the entire transaction is rolled back. 

Conclusion

A database for extremely low latency and massively scalable applications anywhere in the world, with native support for NoSQL. With Microsoft Azure Cosmos DB enterprises of any size can establish a globally distributed database system that takes advantage of already existing data centers and infrastructures in a matter of minutes. Combine that with the administrative tools provided by Azure and Microsoft's intelligent cloud system, and enterprises can establish a powerful global presence quickly and easily without a major initial expenditure.

References - Microsoft