Write concern levels (w: 1, majority) in MongoDB - Mini Project: Build & Apply

Understanding MongoDB Write Concern Levels (w: 1, majority)

📖 Scenario: You are managing a MongoDB database for an online store. You want to ensure that when you add new products, the database confirms the write operation properly to avoid data loss.

🎯 Goal: Learn how to set different write concern levels in MongoDB to control the acknowledgment of write operations, specifically using w: 1 and w: majority.

📋 What You'll Learn

Create a MongoDB collection named products with sample documents.

Set a write concern variable with w: 1.

Insert a new product document using the w: 1 write concern.

Change the write concern to w: majority and insert another product document.

💡 Why This Matters

🌍 Real World

Write concerns help ensure data is safely written to the database, which is critical for applications like online stores where data loss can cause serious problems.

💼 Career

Understanding write concerns is important for database administrators and backend developers to balance data safety and performance in MongoDB.

1

Create the products collection with initial documents

Create a MongoDB collection called products and insert these exact documents: { _id: 1, name: "Laptop", price: 1200 } and { _id: 2, name: "Smartphone", price: 800 }.

MongoDB

// Insert initial documents into the products collection
// Your code here

Need a hint?

Use insertMany to add multiple documents to the products collection.

2

Set a write concern variable with w: 1

Create a variable called writeConcernOne and set it to an object with w: 1.

MongoDB

db.products.insertMany([
  { _id: 1, name: "Laptop", price: 1200 },
  { _id: 2, name: "Smartphone", price: 800 }
])

// Create writeConcernOne variable with w: 1
// Your code here

Need a hint?

Use const to declare the variable and set w: 1 inside an object.

3

Insert a new product using the w: 1 write concern

Use db.products.insertOne() to insert the document { _id: 3, name: "Tablet", price: 600 } with the write concern set to the variable writeConcernOne.

MongoDB

db.products.insertMany([
  { _id: 1, name: "Laptop", price: 1200 },
  { _id: 2, name: "Smartphone", price: 800 }
])

const writeConcernOne = { w: 1 }

// Insert a new product with writeConcernOne
// Your code here

Need a hint?

Pass the write concern as the second argument in insertOne.

4

Set w: majority write concern and insert another product

Create a variable called writeConcernMajority with w: "majority". Then insert the document { _id: 4, name: "Monitor", price: 300 } into products using writeConcernMajority.

MongoDB

db.products.insertMany([
  { _id: 1, name: "Laptop", price: 1200 },
  { _id: 2, name: "Smartphone", price: 800 }
])

const writeConcernOne = { w: 1 }

db.products.insertOne({ _id: 3, name: "Tablet", price: 600 }, { writeConcern: writeConcernOne })

// Create writeConcernMajority and insert a new product with it
// Your code here

Need a hint?

Use w: "majority" in the object and pass it as the write concern option in insertOne.