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Quickstart: Vector search with Node.js in Azure DocumentDB

Use vector search in Azure DocumentDB with the Node.js client library. Store and query vector data efficiently.

This quickstart uses a sample hotel dataset in a JSON file with vectors from the text-embedding-3-small model. The dataset includes hotel names, locations, descriptions, and vector embeddings.

Find the sample code on GitHub.

Prerequisites

  • An Azure subscription

    • If you don't have an Azure subscription, create a free account

Create data file with vectors

  1. Create a new data directory for the hotels data file:

    mkdir data

  2. Copy the Hotels_Vector.json raw data file with vectors to your data directory.

Create a Node.js project

  1. Create a new sibling directory for your project, at the same level as the data directory, and open it in Visual Studio Code:

    mkdir vector-search-quickstart
code vector-search-quickstart

  2. In the terminal, initialize a Node.js project:

    npm init -y
npm pkg set type="module"

  3. Install the required packages:

    npm install mongodb @azure/identity openai @types/node
    • mongodb: MongoDB Node.js driver
    • @azure/identity: Azure Identity library for passwordless authentication
    • openai: OpenAI client library to create vectors
    • @types/node: Type definitions for Node.js

  4. Create a .env file in your project root for environment variables:

    # Identity for local developer authentication with Azure CLI
AZURE_TOKEN_CREDENTIALS=AzureCliCredential

# Azure OpenAI Embedding Settings
AZURE_OPENAI_EMBEDDING_MODEL=text-embedding-3-small
AZURE_OPENAI_EMBEDDING_API_VERSION=2023-05-15
AZURE_OPENAI_EMBEDDING_ENDPOINT=
EMBEDDING_SIZE_BATCH=16

# MongoDB configuration
MONGO_CLUSTER_NAME=

# Data file
DATA_FILE_WITH_VECTORS=../data/Hotels_Vector.json
FIELD_TO_EMBED=Description
EMBEDDED_FIELD=DescriptionVector
EMBEDDING_DIMENSIONS=1536
LOAD_SIZE_BATCH=100

    Replace the placeholder values in the .env file with your own information:

    • AZURE_OPENAI_EMBEDDING_ENDPOINT: Your Azure OpenAI resource endpoint URL
    • MONGO_CLUSTER_NAME: Your resource name

  5. Add a tsconfig.json file to configure TypeScript:

    {
    "compilerOptions": {
        "target": "ES2020",
        "module": "NodeNext",
        "moduleResolution": "nodenext",
        "declaration": true,
        "outDir": "./dist",
        "strict": true,
        "esModuleInterop": true,
        "skipLibCheck": true,
        "noImplicitAny": false,
        "forceConsistentCasingInFileNames": true,
        "sourceMap": true,
        "resolveJsonModule": true,
    },
    "include": [
        "src/**/*"
    ],
    "exclude": [
        "node_modules",
        "dist"
    ]
}

Create npm scripts

Edit the package.json file and add these scripts:

Use these scripts to compile TypeScript files and run the DiskANN index implementation.

"scripts": { 
    "build": "tsc",
    "start:diskann": "node --env-file .env dist/diskann.js"
}

Create a src directory for your TypeScript files. Add two files: diskann.ts and utils.ts for the DiskANN index implementation:

mkdir src    
touch src/diskann.ts
touch src/utils.ts

Paste the following code into the diskann.ts file.

import path from 'path';
import { readFileReturnJson, getClientsPasswordless, insertData, printSearchResults } from './utils.js';

// ESM specific features - create __dirname equivalent
import { fileURLToPath } from "node:url";
import { dirname } from "node:path";
const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const config = {
    query: "quintessential lodging near running trails, eateries, retail",
    dbName: "Hotels",
    collectionName: "hotels_diskann",
    indexName: "vectorIndex_diskann",
    dataFile: process.env.DATA_FILE_WITH_VECTORS!,
    batchSize: parseInt(process.env.LOAD_SIZE_BATCH! || '100', 10),
    embeddedField: process.env.EMBEDDED_FIELD!,
    embeddingDimensions: parseInt(process.env.EMBEDDING_DIMENSIONS!, 10),
    deployment: process.env.AZURE_OPENAI_EMBEDDING_MODEL!,
};

async function main() {

    const { aiClient, dbClient } = getClientsPasswordless();

    try {

        if (!aiClient) {
            throw new Error('AI client is not configured. Please check your environment variables.');
        }
        if (!dbClient) {
            throw new Error('Database client is not configured. Please check your environment variables.');
        }

        await dbClient.connect();
        const db = dbClient.db(config.dbName);
        const collection = await db.createCollection(config.collectionName);
        console.log('Created collection:', config.collectionName);
        const data = await readFileReturnJson(path.join(__dirname, "..", config.dataFile));
        const insertSummary = await insertData(config, collection, data);
        console.log('Created vector index:', config.indexName);
        
        // Create the vector index
        const indexOptions = {
            createIndexes: config.collectionName,
            indexes: [
                {
                    name: config.indexName,
                    key: {
                        [config.embeddedField]: 'cosmosSearch'
                    },
                    cosmosSearchOptions: {
                        kind: 'vector-diskann',
                        dimensions: config.embeddingDimensions,
                        similarity: 'COS', // 'COS', 'L2', 'IP'
                        maxDegree: 20, // 20 - 2048,  edges per node
                        lBuild: 10 // 10 - 500, candidate neighbors evaluated
                    }
                }
            ]
        };
        const vectorIndexSummary = await db.command(indexOptions);

        // Create embedding for the query
        const createEmbeddedForQueryResponse = await aiClient.embeddings.create({
            model: config.deployment,
            input: [config.query]
        });

        // Perform the vector similarity search
        const searchResults = await collection.aggregate([
            {
                $search: {
                    cosmosSearch: {
                        vector: createEmbeddedForQueryResponse.data[0].embedding,
                        path: config.embeddedField,
                        k: 5
                    }
                }
            },
            {
                $project: {
                    score: {
                        $meta: "searchScore"
                    },
                    document: "$$ROOT"
                }
            }
        ]).toArray();

        // Print the results
        printSearchResults(insertSummary, vectorIndexSummary, searchResults);

    } catch (error) {
        console.error('App failed:', error);
        process.exitCode = 1;
    } finally {
        console.log('Closing database connection...');
        if (dbClient) await dbClient.close();
        console.log('Database connection closed');
    }
}

// Execute the main function
main().catch(error => {
    console.error('Unhandled error:', error);
    process.exitCode = 1;
});

This main module provides these features:

  • Includes utility functions
  • Creates a configuration object for environment variables
  • Creates clients for Azure OpenAI and DocumentDB
  • Connects to MongoDB, creates a database and collection, inserts data, and creates standard indexes
  • Creates a vector index using IVF, HNSW, or DiskANN
  • Creates an embedding for a sample query text using the OpenAI client. You can change the query at the top of the file
  • Runs a vector search using the embedding and prints the results

Create utility functions

Paste the following code into utils.ts:

import { MongoClient, OIDCResponse, OIDCCallbackParams } from 'mongodb';
import { AzureOpenAI } from 'openai/index.js';
import { promises as fs } from "fs";
import { AccessToken, DefaultAzureCredential, TokenCredential, getBearerTokenProvider } from '@azure/identity';

// Define a type for JSON data
export type JsonData = Record<string, any>;

export const AzureIdentityTokenCallback = async (params: OIDCCallbackParams, credential: TokenCredential): Promise<OIDCResponse> => {
    const tokenResponse: AccessToken | null = await credential.getToken(['https://ossrdbms-aad.database.windows.net/.default']);
    return {
        accessToken: tokenResponse?.token || '',
        expiresInSeconds: (tokenResponse?.expiresOnTimestamp || 0) - Math.floor(Date.now() / 1000)
    };
};
export function getClients(): { aiClient: AzureOpenAI; dbClient: MongoClient } {
    const apiKey = process.env.AZURE_OPENAI_EMBEDDING_KEY!;
    const apiVersion = process.env.AZURE_OPENAI_EMBEDDING_API_VERSION!;
    const endpoint = process.env.AZURE_OPENAI_EMBEDDING_ENDPOINT!;
    const deployment = process.env.AZURE_OPENAI_EMBEDDING_MODEL!;
    const mongoConnectionString = process.env.MONGO_CONNECTION_STRING!;

    if (!apiKey || !apiVersion || !endpoint || !deployment || !mongoConnectionString) {
        throw new Error('Missing required environment variables: AZURE_OPENAI_EMBEDDING_KEY, AZURE_OPENAI_EMBEDDING_API_VERSION, AZURE_OPENAI_EMBEDDING_ENDPOINT, AZURE_OPENAI_EMBEDDING_MODEL, MONGO_CONNECTION_STRING');
    }

    const aiClient = new AzureOpenAI({
        apiKey,
        apiVersion,
        endpoint,
        deployment
    });
    const dbClient = new MongoClient(mongoConnectionString, {
        // Performance optimizations
        maxPoolSize: 10,         // Limit concurrent connections
        minPoolSize: 1,          // Maintain at least one connection
        maxIdleTimeMS: 30000,    // Close idle connections after 30 seconds
        connectTimeoutMS: 30000, // Connection timeout
        socketTimeoutMS: 360000, // Socket timeout (for long-running operations)
        writeConcern: {          // Optimize write concern for bulk operations
            w: 1,                // Acknowledge writes after primary has written
            j: false             // Don't wait for journal commit
        }
    });

    return { aiClient, dbClient };
}

export function getClientsPasswordless(): { aiClient: AzureOpenAI | null; dbClient: MongoClient | null } {
    let aiClient: AzureOpenAI | null = null;
    let dbClient: MongoClient | null = null;

    // Validate all required environment variables upfront
    const apiVersion = process.env.AZURE_OPENAI_EMBEDDING_API_VERSION!;
    const endpoint = process.env.AZURE_OPENAI_EMBEDDING_ENDPOINT!;
    const deployment = process.env.AZURE_OPENAI_EMBEDDING_MODEL!;
    const clusterName = process.env.MONGO_CLUSTER_NAME!;

    if (!apiVersion || !endpoint || !deployment || !clusterName) {
        throw new Error('Missing required environment variables: AZURE_OPENAI_EMBEDDING_API_VERSION, AZURE_OPENAI_EMBEDDING_ENDPOINT, AZURE_OPENAI_EMBEDDING_MODEL, MONGO_CLUSTER_NAME');
    }

    console.log(`Using Azure OpenAI Embedding API Version: ${apiVersion}`);
    console.log(`Using Azure OpenAI Embedding Deployment/Model: ${deployment}`);

    const credential = new DefaultAzureCredential();

    // For Azure OpenAI with DefaultAzureCredential
    {
        const scope = "https://cognitiveservices.azure.com/.default";
        const azureADTokenProvider = getBearerTokenProvider(credential, scope);
        aiClient = new AzureOpenAI({
            apiVersion,
            endpoint,
            deployment,
            azureADTokenProvider
        });
    }

    // For DocumentDB with DefaultAzureCredential (uses signed-in user)
    {
        dbClient = new MongoClient(
            `mongodb+srv://${clusterName}.mongocluster.cosmos.azure.com/`, {
            connectTimeoutMS: 120000,
            tls: true,
            retryWrites: false,
            maxIdleTimeMS: 120000,
            authMechanism: 'MONGODB-OIDC',
            authMechanismProperties: {
                OIDC_CALLBACK: (params: OIDCCallbackParams) => AzureIdentityTokenCallback(params, credential),
                ALLOWED_HOSTS: ['*.azure.com']
            }
        }
        );
    }

    return { aiClient, dbClient };
}

export async function readFileReturnJson(filePath: string): Promise<JsonData[]> {

    console.log(`Reading JSON file from ${filePath}`);

    const fileAsString = await fs.readFile(filePath, "utf-8");
    return JSON.parse(fileAsString);
}
export async function writeFileJson(filePath: string, jsonData: JsonData): Promise<void> {
    const jsonString = JSON.stringify(jsonData, null, 2);
    await fs.writeFile(filePath, jsonString, "utf-8");

    console.log(`Wrote JSON file to ${filePath}`);
}
export async function insertData(config, collection, data) {
    console.log(`Processing in batches of ${config.batchSize}...`);
    const totalBatches = Math.ceil(data.length / config.batchSize);

    let inserted = 0;
    let updated = 0;
    let skipped = 0;
    let failed = 0;

    for (let i = 0; i < totalBatches; i++) {
        const start = i * config.batchSize;
        const end = Math.min(start + config.batchSize, data.length);
        const batch = data.slice(start, end);

        try {
            const result = await collection.insertMany(batch, { ordered: false });
            inserted += result.insertedCount || 0;
            console.log(`Batch ${i + 1} complete: ${result.insertedCount} inserted`);
        } catch (error: any) {
            if (error?.writeErrors) {
                // Some documents may have been inserted despite errors
                console.error(`Error in batch ${i + 1}: ${error?.writeErrors.length} failures`);
                failed += error?.writeErrors.length;
                inserted += batch.length - error?.writeErrors.length;
            } else {
                console.error(`Error in batch ${i + 1}:`, error);
                failed += batch.length;
            }
        }

        // Small pause between batches to reduce resource contention
        if (i < totalBatches - 1) {
            await new Promise(resolve => setTimeout(resolve, 100));
        }
    }
    const indexColumns = [
        "HotelId",
        "Category",
        "Description",
        "Description_fr"
    ];
    for (const col of indexColumns) {
        const indexSpec = {};
        indexSpec[col] = 1; // Ascending index
        await collection.createIndex(indexSpec);
    }

    return { total: data.length, inserted, updated, skipped, failed };
}

export function printSearchResults(insertSummary, indexSummary, searchResults) {


    if (!searchResults || searchResults.length === 0) {
        console.log('No search results found.');
        return;
    }

    searchResults.map((result, index) => {

        const { document, score } = result as any;

        console.log(`${index + 1}. HotelName: ${document.HotelName}, Score: ${score.toFixed(4)}`);
        //console.log(`   Description: ${document.Description}`);
    });

}

This utility module provides these features:

  • JsonData: Interface for the data structure
  • scoreProperty: Location of the score in query results based on vector search method
  • getClients: Creates and returns clients for Azure OpenAI and Azure DocumentDB
  • getClientsPasswordless: Creates and returns clients for Azure OpenAI and Azure DocumentDB using passwordless authentication. Enable RBAC on both resources and sign in to Azure CLI
  • readFileReturnJson: Reads a JSON file and returns its contents as an array of JsonData objects
  • writeFileJson: Writes an array of JsonData objects to a JSON file
  • insertData: Inserts data in batches into a MongoDB collection and creates standard indexes on specified fields
  • printSearchResults: Prints the results of a vector search, including the score and hotel name

Authenticate with Azure CLI

Sign in to Azure CLI before you run the application so the app can access Azure resources securely.

az login

The code uses your local developer authentication to access Azure DocumentDB and Azure OpenAI with the getClientsPasswordless function from utils.ts. When you set AZURE_TOKEN_CREDENTIALS=AzureCliCredential, this setting tells the function to use Azure CLI credentials for authentication deterministically. The function relies on DefaultAzureCredential from @azure/identity to find your Azure credentials in the environment. Learn more about how to Authenticate JavaScript apps to Azure services using the Azure Identity library.

Build and run the application

Build the TypeScript files, then run the application:

npm run build
npm run start:diskann

The app logging and output show:

  • Collection creation and data insertion status
  • Vector index creation
  • Search results with hotel names and similarity scores
Using Azure OpenAI Embedding API Version: 2023-05-15
Using Azure OpenAI Embedding Deployment/Model: text-embedding-3-small-2
Created collection: hotels_diskann
Reading JSON file from \documentdb-samples\ai\data\Hotels_Vector.json
Processing in batches of 50...
Batch 1 complete: 50 inserted
Created vector index: vectorIndex_diskann
1. HotelName: Royal Cottage Resort, Score: 0.4991
2. HotelName: Country Comfort Inn, Score: 0.4785
3. HotelName: Nordick's Valley Motel, Score: 0.4635
4. HotelName: Economy Universe Motel, Score: 0.4461
5. HotelName: Roach Motel, Score: 0.4388
Closing database connection...
Database connection closed

View and manage data in Visual Studio Code

  1. Select the DocumentDB extension in Visual Studio Code to connect to your Azure DocumentDB account.

  2. View the data and indexes in the Hotels database.

    Screenshot of DocumentDB extension showing the DocumentDB collection.

Clean up resources

Delete the resource group, DocumentDB account, and Azure OpenAI resource when you don't need them to avoid extra costs.

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