MongoDBhard

How does the MongoDB aggregation pipeline work?

Answer

The aggregation pipeline processes documents through ordered stages like $match, $group, $project and $sort. Each stage transforms the stream and passes results to the next one, enabling complex analytics similar to SQL.

[
  { "$match": { "status": "paid" } },
  { "$group": { "_id": "$customerId", "total": { "$sum": "$amount" } } },
  { "$sort": { "total": -1 } }
]

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