1. Definition

The $sort stage is used to arrange documents in a specific order (ascending or descending) based on one or more fields.

2. Simple Understanding

👉 It works like ORDER BY in SQL
👉 It sorts data before sending final results

3. When to Use

• When ordering results
• When showing top or latest data
• When sorting by price, date, or name
• Before applying limit

4. Where it is Used

• Aggregation pipelines
• Search results
• Leaderboard or ranking systems
• Backend APIs

5. Why We Use It

• To organize data meaningfully
• To display ordered results
• To support ranking and pagination
• To prepare data for limit or top queries

6. How It Works

• Uses field values to sort documents
• 1 → ascending order
• -1 → descending order
• Can sort by multiple fields

7. Basic Syntax

db.collection.aggregate([
  { $sort: { age: 1 } } // ascending
]);

db.collection.aggregate([
  { $sort: { age: -1 } } // descending
]);

8. Real Example

// Sort users by age (ascending)
db.users.aggregate([
  { $sort: { age: 1 } }
]);

// Sort users by salary (descending)
db.employees.aggregate([
  { $sort: { salary: -1 } }
]);

// Sort by multiple fields
db.users.aggregate([
  { $sort: { role: 1, age: -1 } }
]);

9. Explanation

• $sort arranges documents in order
• 1 = ascending, -1 = descending
• Can sort multiple fields
• Often used before $limit

10. Advantages

• Organized output
• Supports ranking systems
• Easy to use
• Works well with indexes

11. Disadvantages

• Sorting large data can be slow
• May consume memory
• Requires index for best performance