🍃 MongoDB: Introduction and Key Concepts

1. What is MongoDB?

• MongoDB is a NoSQL, document-oriented database.
• It stores data in JSON-like BSON documents instead of traditional tables and rows.
• Designed for high performance, scalability, and flexibility.

2. Key Features of MongoDB

3. Data Model

• Database contains collections.
• A collection is a group of documents.
• A document is a JSON-like structure made of key-value pairs.

Example document:

{
  "_id": ObjectId("507f1f77bcf86cd799439011"),
  "name": "John Doe",
  "age": 30,
  "address": {
    "street": "123 Main St",
    "city": "New York"
  },
  "hobbies": ["reading", "gaming"]
}

4. CRUD Operations in MongoDB

5. Indexing

• Indexes improve query speed.

• Types of indexes:

  • Single field
  • Compound (multiple fields)
  • Text indexes (for text search)
  • Geospatial indexes (for location-based queries)

Example of creating an index:

db.users.createIndex({age: 1})

6. Replication and Sharding

• Replication: Data copies maintained across multiple servers (replica sets) for availability and fault tolerance.
• Sharding: Splitting data across multiple machines to handle large datasets and high throughput.

7. Aggregation Framework

• Allows data processing and transformation.
• Supports operations like filtering, grouping, sorting, and joining (via $lookup).

Example:

db.orders.aggregate([
  { $match: { status: "shipped" } },
  { $group: { _id: "$customerId", total: { $sum: "$amount" } } }
])

8. Advantages of MongoDB

• Flexible schema fits evolving data models.
• High write performance for big data and real-time apps.
• Easy to scale out via sharding.
• Rich query and aggregation capabilities.
• Strong community and enterprise support.

9. Use Cases

• Content management systems
• Real-time analytics
• Internet of Things (IoT) applications
• Mobile and social networking apps
• Catalog and inventory management

10. Summary Table