MongoDB Method: db.collection.createIndex()

// MongoDB db.collection.createIndex() method examples in Golang

package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	_ "go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

const uri = "mongodb://bigboxuser:bigboxpass@localhost:27017/?maxPoolSize=20&w=majority"

func main() {
	// Initiate mongo client
	mongoClient, err := mongo.Connect(context.TODO(), options.Client().ApplyURI(uri))
	if err != nil {
		fmt.Println("MongoDB connection error: ", err)
		os.Exit(1)
	}
	defer mongoClient.Disconnect(context.Background())

	// Initiate collection instance
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	customerCollection := mongoClient.Database("bigboxcode").Collection("customer")

	// Create unique index
	// email => ascending
	// bigboxcode> db.customer.createIndex({email: 1}, {unique: true})
	createIndexResult, err := customerCollection.Indexes().CreateOne(ctx, mongo.IndexModel{
		Keys:    bson.D{{"email", 1}},
		Options: options.Index().SetUnique(true),
	})

	if err != nil {
		fmt.Println("Command: db.customer.createIndex({email: 1}, {unique: true}) | ERROR: ", err)
	}

	fmt.Println("Command: db.customer.createIndex({email: 1}, {unique: true}) | Result: ", createIndexResult)

	// Set index with name
	// name => ascending
	createIndexResult, err = customerCollection.Indexes().CreateOne(
		context.Background(),
		mongo.IndexModel{
			Keys:    bson.D{{"name", 1}},
			Options: options.Index().SetName("my_name_idx"),
		},
	)

	if err != nil {
		fmt.Println("Command: db.customer.createIndex({name: 1}, {name: \"my_name_idx\"}) | ERROR: ", err)
	}

	fmt.Println("Command: db.customer.createIndex({name: 1}, {name: \"my_name_idx\"}) | Result: ", createIndexResult)

	// Set index
	// address.country => ascending
	// address.state => ascending
	// address.zipcode => hashed
	createIndexResult, err = customerCollection.Indexes().CreateOne(
		context.Background(),
		mongo.IndexModel{
			Keys: bson.D{
				{"address.country", 1},
				{"address.state", 1},
				{"address.zipcode", "hashed"},
			},
		},
	)

	if err != nil {
		fmt.Println("Command: db.customer.createIndex({\"address.country\": 1, \"address.state\" : 1, \"address.zipcode\" : \"hashed\"}) | ERROR: ", err)
	}

	fmt.Println("Command: db.customer.createIndex({\"address.country\": 1, \"address.state\" : 1, \"address.zipcode\" : \"hashed\"}) | Result: ", createIndexResult)

}

Command: db.customer.createIndex({email: 1}, {unique: true}) | Result:  email_1

Command: db.customer.createIndex({name: 1}, {name: "my_name_idx"}) | Result:  my_name_idx

Command: db.customer.createIndex({"address.country": 1, "address.state" : 1, "address.zipcode" : "hashed"}) | Result:  address.country_1_address.state_1_address.zipcode_hashed

// db.collection.createIndex() method example in NodeJS

import { MongoClient } from "mongodb";

async function main() {
  // Define MongoDB connection URI
  const uri = "mongodb://bigboxuser:bigboxpass@127.0.0.1:27017";

  // Create a client
  const mongo = new MongoClient(uri);

  try {
    await mongo.connect();

    const database = mongo.db("bigboxcode");
    const customerCollection = database.collection("customer");

    // Create unique index on email field
    let commandResult = await customerCollection.createIndex(
      { email: 1 },
      { unique: true }
    );

    console.log(
      "Command: db.customer.createIndex({email: 1}, {unique: true}) | Result:",
      commandResult
    );

    // Check indexes
    commandResult = await customerCollection.indexes();

    console.log("Command: db.customer.getIndexes() | Result:", commandResult);

    // Set index with name
    commandResult = await customerCollection.createIndex(
      { name: 1 },
      { name: "my_name_idx" }
    );

    console.log(
      'Command: db.customer.createIndex({name: 1}, {name: "my_name_idx"}) | Result: ',
      commandResult
    );

    // Check indexes
    commandResult = await customerCollection.indexes();
    console.log("Command: db.customer.getIndexes() | Result:", commandResult);

    // Set compound index on address fields with hashed zipcode
    await customerCollection.createIndex(
      { "address.country": 1, "address.state": 1, "address.zipcode": "hashed" },
      { name: "address.country_1_address.state_1_address.zipcode_hashed" }
    );

    console.log(
      'Command: Command: db.customer.createIndex({"address.country": 1, "address.state" : 1, "address.zipcode" : "hashed"}) | Result: ',
      commandResult
    );

    // Check indexes
    commandResult = await customerCollection.indexes();
    console.log("Command: db.customer.getIndexes() | Result:", commandResult);
  } finally {
    await mongo.close();
  }
}

await main().catch(console.error);

process.exit(0);

Command: db.customer.createIndex({email: 1}, {unique: true}) | Result: email_1
Command: db.customer.getIndexes() | Result: [
  { v: 2, key: { _id: 1 }, name: '_id_' },
  { v: 2, key: { email: 1 }, name: 'email_1', unique: true }
]
Command: db.customer.createIndex({name: 1}, {name: "my_name_idx"}) | Result:  my_name_idx
Command: db.customer.getIndexes() | Result: [
  { v: 2, key: { _id: 1 }, name: '_id_' },
  { v: 2, key: { email: 1 }, name: 'email_1', unique: true },
  { v: 2, key: { name: 1 }, name: 'my_name_idx' }
]
Command: Command: db.customer.createIndex({"address.country": 1, "address.state" : 1, "address.zipcode" : "hashed"}) | Result:  [
  { v: 2, key: { _id: 1 }, name: '_id_' },
  { v: 2, key: { email: 1 }, name: 'email_1', unique: true },
  { v: 2, key: { name: 1 }, name: 'my_name_idx' }
]
Command: db.customer.getIndexes() | Result: [
  { v: 2, key: { _id: 1 }, name: '_id_' },
  { v: 2, key: { email: 1 }, name: 'email_1', unique: true },
  { v: 2, key: { name: 1 }, name: 'my_name_idx' },
  {
    v: 2,
    key: {
      'address.country': 1,
      'address.state': 1,
      'address.zipcode': 'hashed'
    },
    name: 'address.country_1_address.state_1_address.zipcode_hashed'
  }
]

# db.collection.createIndex() method example in Python

from pymongo import MongoClient, WriteConcern
import re
from datetime import datetime

# Create MongoDB client
mongo_client = MongoClient("mongodb://bigboxuser:bigboxpass@127.0.0.1:27017/")

# Select database and collection
mongo_database = mongo_client.bigboxcode
customer_collection = mongo_database.customer

try:
    # Create unique index on email field
    command_result = customer_collection.create_index([("email", 1)], unique=True)

    print(
        "Command: db.customer.createIndex({email: 1}, {unique: true}) | Result:",
        command_result,
    )

    # Check indexes
    command_result = customer_collection.index_information()
    print("Indexes:", command_result)

    # Set index with name
    command_result = customer_collection.create_index([("name", 1)], name="my_name_idx")

    print(
        'Command: db.customer.createIndex({name: 1}, {name: "my_name_idx"}) | Result:',
        command_result,
    )

    # Check indexes
    command_result = customer_collection.index_information()
    print("Indexes:", command_result)

    # Set compound index on address fields with hashed zipcode
    command_result = customer_collection.create_index(
        [("address.country", 1), ("address.state", 1), ("address.zipcode", "hashed")],
        name="address.country_1_address.state_1_address.zipcode_hashed",
    )

    print(
        'Command: Command: db.customer.createIndex({"address.country": 1, "address.state" : 1, "address.zipcode" : "hashed"}) | Result:',
        command_result,
    )

    # Check indexes
    command_result = customer_collection.index_information()
    print("Indexes:", command_result)
finally:
    mongo_client.close()

Command: db.customer.createIndex({email: 1}, {unique: true}) | Result: email_1

Indexes: {'_id_': {'v': 2, 'key': [('_id', 1)]}, 'email_1': {'v': 2, 'key': [('email', 1)], 'unique': True}}

Command: db.customer.createIndex({name: 1}, {name: "my_name_idx"}) | Result: my_name_idx

Indexes: {'_id_': {'v': 2, 'key': [('_id', 1)]}, 'email_1': {'v': 2, 'key': [('email', 1)], 'unique': True}, 'my_name_idx': {'v': 2, 'key': [('name', 1)]}}

Command: Command: db.customer.createIndex({"address.country": 1, "address.state" : 1, "address.zipcode" : "hashed"}) | Result: address.country_1_address.state_1_address.zipcode_hashed

Indexes: {'_id_': {'v': 2, 'key': [('_id', 1)]}, 'email_1': {'v': 2, 'key': [('email', 1)], 'unique': True}, 'my_name_idx': {'v': 2, 'key': [('name', 1)]}, 'address.country_1_address.state_1_address.zipcode_hashed': {'v': 2, 'key': [('address.country', 1), ('address.state', 1), ('address.zipcode', 'hashed')]}}

// db.collection.createIndex() method example in Java

import com.mongodb.client.*;
import com.mongodb.client.model.IndexOptions;
import org.bson.Document;

public class CreateIndex {
    public static void main(String[] args) {
        String uri = "mongodb://bigboxuser:bigboxpass@localhost:27017/";

        try (MongoClient mongoClient = MongoClients.create(uri)) {
            MongoDatabase database = mongoClient.getDatabase("bigboxcode");
            MongoCollection<Document> customerCollection = database.getCollection("customer");

            // Create unique index on email field
            customerCollection.createIndex(new Document("email", 1), new IndexOptions().unique(true));

            // Check indexes
            System.out.println("Indexes:");
            for (Document index : customerCollection.listIndexes()) {
                System.out.println(index.toJson());
            }

            // Set index with name
            customerCollection.createIndex(new Document("name", 1), new IndexOptions().name("my_name_idx"));

            // Check indexes
            System.out.println("Indexes:");
            for (Document index : customerCollection.listIndexes()) {
                System.out.println(index.toJson());
            }

            // Set compound index on address fields with hashed zipcode
            customerCollection.createIndex(
                    new Document("address.country", 1)
                            .append("address.state", 1)
                            .append("address.zipcode", "hashed")
            );

            // Check indexes
            System.out.println("Indexes:");
            for (Document index : customerCollection.listIndexes()) {
                System.out.println(index.toJson());
            }
            mongoClient.close();

        }
    }
}

Indexes:
{"v": 2, "key": {"_id": 1}, "name": "_id_"}
{"v": 2, "key": {"email": 1}, "name": "email_1", "unique": true}

Indexes:
{"v": 2, "key": {"_id": 1}, "name": "_id_"}
{"v": 2, "key": {"email": 1}, "name": "email_1", "unique": true}
{"v": 2, "key": {"name": 1}, "name": "my_name_idx"}

Indexes:
{"v": 2, "key": {"_id": 1}, "name": "_id_"}
{"v": 2, "key": {"email": 1}, "name": "email_1", "unique": true}
{"v": 2, "key": {"name": 1}, "name": "my_name_idx"}
{"v": 2, "key": {"address.country": 1, "address.state": 1, "address.zipcode": "hashed"}, "name": "address.country_1_address.state_1_address.zipcode_hashed"}