Azure Cosmos DB: Getting Started with the Multi-Model Database

Cosmos DB is Azure’s globally distributed, multi-model database. It’s different from SQL Server in fundamental ways. Here’s what you need to know to get started.

Key Concepts

• Global distribution: Replicate data across regions with a click
• Multi-model: Document, key-value, graph, column-family APIs
• Guaranteed latency: <10ms reads/writes at 99th percentile
• Elastic scale: Throughput and storage scale independently

Request Units (RU/s)

Cosmos DB pricing is based on Request Units. Think of it as a normalized measure of throughput:

1 RU = 1 KB document read
~5 RUs = 1 KB document write
Complex queries = more RUs

.NET Example

var client = new CosmosClient(connectionString);
var container = client.GetContainer("mydb", "items");

// Create
await container.CreateItemAsync(item, new PartitionKey(item.Category));

// Read
var response = await container.ReadItemAsync(id, new PartitionKey(category));

When to Use It

• Global applications needing low latency everywhere
• High-throughput scenarios (IoT, gaming)
• Document-oriented data models

References

• Cosmos DB Documentation