Learn MongoDB | Sujal Magar

1. Introduction

MongoDB is a NoSQL document-oriented database that stores data in flexible JSON-like documents (BSON).

It is designed for scalability, flexibility, and high performance.

Example:

{
  "name": "Alice",
  "age": 25,
  "skills": ["Python", "SQL"]
}

collection.insert_one({"name":"Alice"})

collection.find({"age": {"$gt": 20}})

collection.update_one(
  {"name":"Alice"},
  {"$set":{"age":26}}
)

collection.delete_one({"name":"Alice"})

Two approaches:

collection.create_index("name")

Improves read performance.

Processes data in stages.

Example:

pipeline = [
  {"$match": {"age": {"$gt": 20}}},
  {"$group": {"_id": "$age", "count": {"$sum": 1}}}
]
collection.aggregate(pipeline)

Replica sets provide:

Distributes data across servers.

Used for big data scaling.

Supported in modern MongoDB versions.