Book Image

Learning Azure Cosmos DB

By : Shahid Shaikh
Book Image

Learning Azure Cosmos DB

By: Shahid Shaikh

Overview of this book

<p>Microsoft has introduced a new globally distributed database, called Azure Cosmos DB. It is a superset of Microsoft's existing NoSQL Document DB service. Azure Cosmos DB enables you to scale throughput and storage elastically and independently across any number of Azure's geographic regions.</p> <p>This book is a must-have for anyone who wants to get introduced to the world of Cosmos DB. This book will focus on building globally-distributed applications without the hassle of complex, multiple datacenter configurations. This book will shed light on how Cosmos DB offers multimodal NoSQL database capabilities in the cloud at a scale that is one product with different database engines, such as key-value, document, graph, and wide column store. We will cover detailed practical examples on how to create a CRUD application using Cosmos DB with a frontend framework of your choice. This book will empower developers to choose their favorite database engines to perform integration, along with other systems that utilize the most popular languages, such as Node.js. This book will take you through the tips and trick, of Cosmos DB deployment, management, and the security offered by Azure Cosmos DB in order to detect, prevent, and respond to database breaches.</p> <p>By the end of this book, you will not only be aware of the best capabilities of relational and non-relational databases, but you will also be able to build scalable, globally distributed,<br />and highly responsive applications.</p>
Table of Contents (14 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Failover handling


When something fails, what's going to happen?

This is the key question of any deployment, because it matters. Consider applications like WhatsApp; if they go down, even for a minute, then the user base is going to go crazy. With your application, too, if the system fails, then you are going to lose users but, more importantly, you are also going to lose your reputation.

Cosmos DB is a managed database provider and I believe that they care about failover a lot. There are generally two ways to handle failover:

  • Automatic failover
  • Manual failover

Let's discuss each of them.

Automatic failover

In rare cases of a system outage, automatic failover tries to recover and reassign the traffic to the existing regions. There are generally two cases where this applies:

  • Read region failover
  • Write region failover

If any read regions fails, Cosmos DB automatically marks them offline, in order to avoid any existing traffic trying to route to that region (to avoid 404 and 502 errors), and, using the...