Book Image

Guide to NoSQL with Azure Cosmos DB

By : Gaston C. Hillar, Daron Yöndem
Book Image

Guide to NoSQL with Azure Cosmos DB

By: Gaston C. Hillar, Daron Yöndem

Overview of this book

Cosmos DB is a NoSQL database service included in Azure that is continuously adding new features and has quickly become one of the most innovative services found in Azure, targeting mission-critical applications at a global scale. This book starts off by showing you the main features of Cosmos DB, their supported NoSQL data models and the foundations of its scalable and distributed architecture. You will learn to work with the latest available tools that simplify your tasks with Cosmos DB and reduce development costs, such as the Data Explorer in the Azure portal, Microsoft Azure Storage Explorer, and the Cosmos DB Emulator. Next, move on to working with databases and document collections. We will use the tools to run schema agnostic queries against collections with the Cosmos DB SQL dialect and understand their results. Then, we will create a first version of an application that uses the latest .NET Core SDK to interact with Cosmos DB. Next, we will create a second version of the application that will take advantage of important features that the combination of C# and the .NET Core SDK provides, such as POCOs and LINQ queries. By the end of the book, you will be able to build an application that works with a Cosmos DB NoSQL document database with C#, the .NET Core SDK, LINQ, and JSON.
Table of Contents (13 chapters)
Title Page
Packt Upsell

Taking advantage of regional failover

You might have noticed that on the Replicate data globally page in the Azure portal, there is only one region defined as Write region. This is because Cosmos DB is designed to get all writes into a single region and distribute the reads.

Cosmos DB started supporting multiple write regions with a feature called Multi-Master in a preview version during the last quarter of 2018. With a single write region, it is important to plan for regional failovers. When a read region fails, another region will take over. When a write region fails, you might want to prioritize what region to take over explicitly. To do so, you can find an Automatic Failover button on top of the region replication blade. Once you open up the page, you can enable automatic failover and drag and drop regions to create your prioritized failover list.

The following screenshot shows a sample configuration for the read regions and its priorities:

In addition to automatic failovers, you can change...