Introduction to Azure Cosmos DB

What is Azure Cosmos DB?

Azure Cosmos DB is a globally distributed, multi-model database service that enables you to create and interact with massively scalable, high-performance data solutions. It offers a choice of APIs, including SQL (Core API), MongoDB, Cassandra, Gremlin, and Table, providing flexibility to choose the best API for your application.

Key features of Azure Cosmos DB include:

Global Distribution: Distribute your data across any number of Azure regions worldwide.
Elastic Scalability: Scale throughput and storage independently and elastically.
Guaranteed Low Latency: Offer sub-millisecond latency for reads and writes globally.
Multi-Model: Supports various data models and APIs.
High Availability: Built-in, automatic failover for mission-critical applications.

Key Concepts

Understanding these core concepts is crucial for working with Azure Cosmos DB:

Account: Your Cosmos DB resource in Azure. It can contain multiple databases.
```
Azure Portal -> Create a resource -> Azure Cosmos DB
```
Database: A logical namespace for your data. A Cosmos DB account can have multiple databases.
Container: The unit of physical storage and throughput for your data. Containers can store data of different types, but typically store items of the same kind. A container is defined by a name and a partition key.
Item: The actual data stored within a container. In the SQL API, items are JSON documents.
Partition Key: A property within your items that determines how your data is distributed across logical partitions. Choosing a good partition key is vital for performance and scalability.
Request Units (RUs): A measure of throughput. One RU represents the amount of computational work needed to perform a database operation, such as a read or write.

Getting Started with Cosmos DB (SQL API)

Let's walk through the basic steps to create and interact with a Cosmos DB container using the SQL API.

1. Create an Azure Cosmos DB Account

You can create an account via the Azure portal, Azure CLI, or Azure PowerShell.

                Azure CLI:
                
az cosmosdb create --name <your-cosmosdb-account-name> --resource-group <your-resource-group> --kind GlobalDocumentDB --locations regionName="West US" isZoneRedundant="false" regionName="East US" isZoneRedundant="false"

2. Create a Database and Container

Once the account is created, you can create a database and a container. We'll use a sample JSON document structure for demonstration.

Illustrative view of creating a container in the Azure portal.

Container Configuration:

Database: TasksDB
Container: Items
Partition Key: /category

Example JSON item:


{
    "id": "6b43035e-51b2-44e6-900a-c1a267f57739",
    "name": "Cosmos DB Tutorial Item",
    "description": "This is a sample item for the tutorial.",
    "isComplete": false,
    "category": "tutorial",
    "tags": ["cosmosdb", "azure", "tutorial"]
}

3. Querying Data

You can query your data using the SQL API, which uses a SQL-like syntax. Here's an example to retrieve items where the category is 'tutorial':


SELECT * FROM c WHERE c.category = "tutorial"

You can execute these queries directly in the Azure portal's Data Explorer, or programmatically using Azure SDKs.

What's Next?

This introduction covered the basics of Azure Cosmos DB. To dive deeper, consider exploring:

Refer to the official Azure Cosmos DB documentation for comprehensive details and advanced tutorials.