MongoDB Database Management

Introduction to MongoDB
Installation and Setup
CRUD Operations
Data Modeling
Aggregation Framework
Indexing and Performance
Database Administration
Best Practices

Introduction to MongoDB

MongoDB is a document-oriented NoSQL database that provides high performance, high availability, and easy scalability. It stores data in flexible, JSON-like documents.

Key Features:

Document-oriented storage
High scalability
Rich query language
High availability with replica sets
Horizontal scaling with sharding
Support for ad hoc queries

Why MongoDB?

Flexible schema design
Handles large volumes of unstructured data
Native scaling capabilities
Rich ecosystem and tooling
Strong community support

Installation and Setup

Installation Steps

# Ubuntu/Debian
wget -qO - https://www.mongodb.org/static/pgp/server-6.0.asc | sudo apt-key add -
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/6.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-6.0.list
sudo apt update
sudo apt install -y mongodb-org

# Start MongoDB
sudo systemctl start mongod
sudo systemctl enable mongod

# Verify installation
mongosh

Basic Configuration

# mongod.conf
storage:
  dbPath: /var/lib/mongodb
systemLog:
  destination: file
  path: /var/log/mongodb/mongod.log
net:
  port: 27017
  bindIp: 127.0.0.1
security:
  authorization: enabled

CRUD Operations

Create Operations

// Insert a single document
db.users.insertOne({
    name: "John Doe",
    email: "john@example.com",
    age: 30
});

// Insert multiple documents
db.users.insertMany([
    { name: "Jane Smith", email: "jane@example.com" },
    { name: "Bob Johnson", email: "bob@example.com" }
]);

Read Operations

// Find documents
db.users.find({ age: { $gt: 25 } });

// Find one document
db.users.findOne({ email: "john@example.com" });

// Query with projection
db.users.find(
    { age: { $gt: 25 } },
    { name: 1, email: 1, _id: 0 }
);

Update Operations

// Update one document
db.users.updateOne(
    { email: "john@example.com" },
    { $set: { age: 31 } }
);

// Update multiple documents
db.users.updateMany(
    { age: { $lt: 30 } },
    { $inc: { age: 1 } }
);

Delete Operations

// Delete one document
db.users.deleteOne({ email: "john@example.com" });

// Delete multiple documents
db.users.deleteMany({ age: { $lt: 18 } });

Data Modeling

Document Structure

// Embedded Documents
db.orders.insertOne({
    orderId: "12345",
    customer: {
        name: "John Doe",
        email: "john@example.com",
        address: {
            street: "123 Main St",
            city: "Boston",
            state: "MA"
        }
    },
    items: [
        { product: "Laptop", price: 999.99, quantity: 1 },
        { product: "Mouse", price: 24.99, quantity: 2 }
    ]
});

References

// Referenced Documents
db.products.insertOne({
    _id: ObjectId("..."),
    name: "Laptop",
    price: 999.99
});

db.orders.insertOne({
    customer_id: ObjectId("..."),
    product_ids: [ObjectId("...")]
});

// Lookup referenced documents
db.orders.aggregate([
    {
        $lookup: {
            from: "products",
            localField: "product_ids",
            foreignField: "_id",
            as: "products"
        }
    }
]);

Aggregation Framework

Pipeline Stages

// Basic aggregation
db.orders.aggregate([
    { $match: { status: "completed" } },
    { $group: {
        _id: "$customer_id",
        total: { $sum: "$total" },
        count: { $sum: 1 }
    }},
    { $sort: { total: -1 } }
]);

// Complex aggregation
db.sales.aggregate([
    {
        $match: {
            date: {
                $gte: ISODate("2025-01-01"),
                $lt: ISODate("2026-01-01")
            }
        }
    },
    {
        $group: {
            _id: {
                month: { $month: "$date" },
                year: { $year: "$date" }
            },
            totalSales: { $sum: "$amount" },
            avgSale: { $avg: "$amount" }
        }
    },
    {
        $sort: {
            "_id.year": 1,
            "_id.month": 1
        }
    }
]);

Indexing and Performance

Index Types

// Single field index
db.users.createIndex({ email: 1 });

// Compound index
db.products.createIndex({ 
    category: 1, 
    name: 1 
});

// Text index
db.articles.createIndex({ 
    content: "text", 
    title: "text" 
});

// Geospatial index
db.locations.createIndex({ 
    coordinates: "2dsphere" 
});

Query Optimization

// Explain query plan
db.users.find({ age: { $gt: 25 } }).explain("executionStats");

// Index usage stats
db.collection.aggregate([
    { $indexStats: {} }
]);

Database Administration

User Management

// Create user
db.createUser({
    user: "appUser",
    pwd: "secure123",
    roles: [
        { role: "readWrite", db: "myapp" },
        { role: "read", db: "reporting" }
    ]
});

// Grant roles
db.grantRolesToUser("appUser", [
    { role: "dbAdmin", db: "myapp" }
]);

Backup and Recovery

# Create backup
mongodump --db=myapp --out=/backup/

# Restore backup
mongorestore --db=myapp /backup/myapp/

# Point-in-time recovery
mongodump --db=myapp --oplog
mongorestore --oplogReplay

Best Practices

Schema Design

Design for most frequent queries
Consider document growth
Limit array sizes
Use appropriate data types
Balance embedding vs referencing

Performance

Create proper indexes
Monitor query performance
Use appropriate write concern
Consider data lifecycle management
Implement proper backup strategy

MongoDB Database Management

Contents

Introduction to MongoDB

Key Features:

Why MongoDB?

Installation and Setup

Installation Steps

Basic Configuration

CRUD Operations

Create Operations

Read Operations

Update Operations

Delete Operations

Data Modeling

Document Structure

References

Aggregation Framework

Pipeline Stages

Indexing and Performance

Index Types

Query Optimization

Database Administration

User Management

Backup and Recovery

Best Practices

Schema Design

Performance