Azure Cosmos DB NoSQL Tutorial

Overview

Azure Cosmos DB is a fully managed NoSQL database service that offers turnkey global distribution, low latency, and multi‑model support. This tutorial walks you through provisioning a Cosmos DB account, creating a database and container, and performing CRUD operations using the Azure portal and SDK.

Getting Started

Prerequisites:

Azure subscription
Azure CLI or Azure Portal access
Node.js (v14+) installed locally

1. Sign in to Azure Portal and search for Cosmos DB. 2. Click Create → Core (SQL) (NoSQL). 3. Fill out the form (resource group, account name, API = Core (SQL)), then click Review + create.

Create a Database

Using Azure Portal:

Navigate to your Cosmos DB account.
Select Data Explorer → New Database.
Enter TutorialDB as the name and set Throughput to 400 RU/s.
Click OK.

Using Azure CLI:

az cosmosdb sql database create \
    --account-name MyCosmosAccount \
    --resource-group MyResourceGroup \
    --name TutorialDB \
    --throughput 400

Create a Container

Container stores your items. Define a partition key for efficient scaling.

az cosmosdb sql container create \
    --account-name MyCosmosAccount \
    --resource-group MyResourceGroup \
    --database-name TutorialDB \
    --name Items \
    --partition-key-path "/category"

Resulting container:

Name	Partition Key	Throughput
Items	/category	400 RU/s

Query Data with Node.js SDK

Install the SDK:

npm install @azure/cosmos

Sample script (save as app.js):

const { CosmosClient } = require("@azure/cosmos");
const endpoint = "https://<your-account>.documents.azure.com:443/";
const key = "<your-primary-key>";
const client = new CosmosClient({ endpoint, key });

async function run() {
  const database = client.database("TutorialDB");
  const container = database.container("Items");

  // Create item
  const { resource: createdItem } = await container.items.create({
    id: "item1",
    category: "books",
    title: "Learn Azure Cosmos DB",
    price: 29.99
  });
  console.log("Created item:", createdItem.id);

  // Query items
  const querySpec = {
    query: "SELECT * FROM c WHERE c.category = @category",
    parameters: [{ name: "@category", value: "books" }]
  };
  const { resources: results } = await container.items.query(querySpec).fetchAll();
  console.log("Query results:", results);
}
run().catch(console.error);

Scaling & Throughput

Cosmos DB offers two throughput models:

Provisioned RU/s: Fixed throughput; ideal for predictable workloads.
Serverless: Pay-per-request; best for sporadic traffic.

Enable autoscale to automatically adjust RU/s up to a maximum you define.

az cosmosdb sql container update \
    --account-name MyCosmosAccount \
    --resource-group MyResourceGroup \
    --database-name TutorialDB \
    --name Items \
    --throughput-autoscale-max 4000

Best Practices

Choose a partition key with high cardinality and even data distribution.
Leverage point reads (ReadItemAsync) for low latency.
Use TTL to auto-delete stale data when appropriate.
Monitor RU consumption with Azure Monitor and set alerts.
Enable Multi‑Region Writes for active‑active solutions.