Dear DocumentDB customers,

We are very excited that you are now a part of the Azure Cosmos DB family!

Azure Cosmos DB, announced at the Microsoft Build 2017 conference, is the first 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. Designed as a globally distributed database system, Cosmos DB automatically replicates all of your data to any number of regions of your choice, for fast, responsive access. Cosmos DB supports transparent multi-homing and guarantees 99.99% high availability.

Only Cosmos DB allows you to use key-value, graph, and document data in one service, at global scale and without worrying about schema or index management. Cosmos DB allows you to use your favorite API including SQL (Document DB), JavaScript, Gremlin, MongoDB, and Azure Table storage to query your data. As the first and only schema-agnostic database, regardless of the data model, Azure Cosmos DB automatically indexes all your data to eliminate any friction, so you can perform blazing fast queries and focus on your app.

One of the APIs Azure Cosmos DB supports is the SQL (DocumentDB) API and the document data-model. You're already very well familiar with it and already using it to run your current DocumentDB applications. You are already using to run your current DocumentDB applications. These APIs are not changing - the NuGet package, the namespaces, and all dependencies remain the same. You don't need to change anything to continue running your apps built with SQL (DocumentDB) API. You are simply now a part of the service that gives you more capabilities at your disposal.

Why the move to Azure Cosmos DB?

The Cosmos DB project started in 2010 as “Project Florence” to address developer pain-points that are faced by large Internet-scale applications inside Microsoft. Observing that these problems are not unique to Microsoft’s applications, we decided to make Cosmos DB generally available to external developers in 2015 in the form of Azure DocumentDB – the service you’ve been using. The exponential growth of the service has validated our design choices and the unique tradeoffs we have made.

Azure Cosmos DB is the next big leap in globally distributed, at scale, cloud databases. As a DocumentDB customer, you now have access to the new breakthrough system and capabilities offered by Azure Cosmos DB. As a part of this release of Azure Cosmos DB, DocumentDB customers, with their data, are automatically Azure Cosmos DB customers. The transition is seamless and you now have access to all capabilities offered by Azure Cosmos DB. These capabilities are in the areas of the core database engine as well as global distribution, elastic scalability, and industry-leading, comprehensive SLAs.

Specifically, Cosmos DB is all about providing intelligent choices to developers and enabling you to build planet scale apps.

Cosmos DB exposes multiple well-defined consistency models : Databases today only offer two extreme choices for consistency – “strong” consistency and “eventual” consistency. In contrast, Cosmos DB is the first production globally distributed database service to have harvested a set of useful consistency models from decades of research and have operationalized them. Cosmos DB offers five well-defined consistency models which provide clear tradeoffs with respect to latency/availability, backed by SLAs.

Cosmos DB allows developers to model real world in its true form : No data is born relational. Cosmos DB allows developers to store and query their data in its original form. It exposes graph, documents, key-values, column-family data models and will enable others. The multi-model and multi-API capabilities remove the friction, allowing you to build with any data model and API.

Cosmos DB meets developers where they are : Cosmos DB offers a multitude of APIs to access and query data including, SQL and various popular OSS APIs.

What are the extra capabilities you get?

The current developer facing manifestation of this work is the new support for Gremlin and Table Storage APIs. And this is just the beginning… We will be adding other popular APIs and newer data models over time with more advances towards performance and storage at global scale.

It is important to point out that DocumentDB’s SQL dialect has always been just one of the many APIs that the underlying Cosmos DB was capable of supporting. As a developer using a fully managed service like Azure Cosmos DB, the only interface to the service is the APIs exposed by the service. To that end, nothing really changes for you as an existing DocumentDB customer. Azure Cosmos DB offers exactly the same SQL API that DocumentDB did. However, now (and in the future) you can get access to other capabilities, which were previously not accessible.

Another manifestation of our continued work is the extended foundation for global and elastic scalability of throughput and storage. One of the very first manifestations of it is the RU/m but we have more capabilities that we will be announcing in these areas. These new capabilities help reduce costs for our customers for various workloads. Please read our recent blog on RU/m here. We have made several foundational enhancements to the global distribution subsystem. One of the many developer facing manifestations of this work is the consistent prefix consistency model (making in total five well-defined consistency models). However, there are many more interesting capabilities we will release as they mature.

If you still have more questions

Here you can read the answers to the most frequently asked questions by other DocumentDB customers about Cosmos DB experience.

Next Steps

Thank you for being our customers! Cosmos DB wouldn’t be the same without you. We brought together your feedback, decades of distributed systems research combined with superb engineering and craftsmanship to create this service. Azure Cosmos DB is the database of the future – it is what we believe is the next big thing in the world of massively scalable databases! It makes your data available close to where your users are, worldwide. Our mission is to be the most trusted database service in the world and to enable you to build amazingly powerful, cosmos-scale apps, more easily.

Next, we recommend you:

Read these: Azure Cosmos DB announcement blog and the technical overview blog

Understand the core concepts of Azure Cosmos DB

Learn more about the service and its capabilities by reading the documentation

Visit the pricing page to understand the billing

Try out the new capabilities in Azure Cosmos DB and let us know what you think! If you need any help or have questions or feedback, please reach out to us through askcosmosdb@microsoft.com. Stay up-to-date on the latest Azure Cosmos DB news (#CosmosDB) and features by following us on Twitter @AzureCosmosDB and join our LinkedIn Group. We are really excited to see what you will build with Cosmos DB.

— Your friends at Azure Cosmos DB @AzureCosmosDB