Introduction to Azure Cosmos DB

Azure Cosmos DB is a globally distributed, multi-model database service. It provides comprehensive SLA-backed guarantees on availability, latency, throughput, and consistency.

What is Azure Cosmos DB?

Azure Cosmos DB is Microsoft's globally distributed, multi-model database system. It allows you to read and write data at the speed of light, with transparently partitioned global distribution, and guaranteed low latency.

It's designed for modern application development, offering:

Global Distribution: Distribute your data across any number of Azure regions worldwide.
Multi-Model Support: Supports multiple data models including document, key-value, graph, and column-family.
Guaranteed Throughput: Offers SLA-backed throughput guarantees.
Low Latency: Provides single-digit millisecond latency for reads and writes.
High Availability: Offers SLA-backed availability guarantees.
Tunable Consistency: Provides five well-defined consistency levels, from strong to eventual.

Key Features and Benefits

Globally Distributed

With Azure Cosmos DB, you can distribute your data to any number of Azure regions. This allows you to place data close to your users, providing them with faster access and a better user experience. You can also replicate your data across multiple regions for high availability and disaster recovery.

Multi-Model Capabilities

Cosmos DB is the first and only globally distributed database service that supports the following core API families:

Azure Cosmos DB for NoSQL (formerly DocumentDB): A document database.
Azure Cosmos DB for MongoDB: API for MongoDB applications.
Azure Cosmos DB for Cassandra: API for Apache Cassandra applications.
Azure Cosmos DB for Gremlin: API for Apache TinkerPop graph data.
Azure Cosmos DB for Table: API for Azure Table storage applications.

This flexibility allows developers to use the API that best suits their existing application or their specific needs without vendor lock-in.

Scalability and Performance

Cosmos DB is designed for massive scalability. You can scale your throughput and storage up or down on demand. It offers elastic scaling, allowing you to provision throughput (measured in Request Units per second, or RU/s) and storage independently for each container or database.


            // Example of provisioning RU/s
            const throughput = {
                container: 1000, // 1000 RU/s for a container
                database: 4000 // 4000 RU/s for a database
            };

Guaranteed SLAs

Azure Cosmos DB is the only cloud database service that offers comprehensive, SLA-backed guarantees for:

Availability: 99.999% for multi-region availability.
Throughput: 99.999% for single-region availability.
Latency: Guaranteed low latency (under 10 ms for reads, under 15 ms for writes).
Consistency: Guaranteed throughput and availability.

Tunable Consistency Models

Cosmos DB offers five distinct consistency levels:

Strong: All reads are guaranteed to return the most recent committed write.
Bounded Staleness: Reads are guaranteed to be no more than a specified number of versions or time interval behind the write.
Session: Reads within the same session are guaranteed to be consistent.
Consistent Prefix: Writes are guaranteed to be returned in the order they were written.
Eventual: No guarantee of reads beyond consistency within a session.

You can choose the consistency level that best balances consistency, availability, and performance for your application.

Tip: For most applications, using session consistency provides a good balance between performance and consistency.

Use Cases

Azure Cosmos DB is ideal for a wide range of applications, including:

IoT (Internet of Things): Ingesting and querying massive amounts of telemetry data.
Web and Mobile Applications: Storing user profiles, session state, and product catalogs.
Gaming: Storing player data, leaderboards, and game state.
E-commerce: Managing product catalogs, shopping carts, and orders.
Real-time Analytics: Processing and analyzing streaming data.

Getting Started

To start using Azure Cosmos DB, you can create an account in the Azure portal. You can then create databases, containers, and start adding your data. Cosmos DB provides SDKs for various programming languages to interact with your data.

For more detailed information, explore the subsequent sections on specific APIs and configuration options.

Note: Azure Cosmos DB is a premium database service. Be mindful of your provisioned throughput (RU/s) and storage consumption to manage costs effectively.