MongoDB $group

The $group stage in MongoDB is similar to SQL’s GROUP BY.

Example

{
  "$group": {
    "_id": "$category",
    "totalSales": { "$sum": "$amount" },
    "avgSale": { "$avg": "$amount" }
  }
}

This groups by category and calculates total + average sales.

Common Operators

• $sum → Adds numbers
• $avg → Calculates average
• $max / $min → Finds extremes
• $push → Creates an array

Always pair $group with $sort for cleaner results.