midMongoDB
Explain the Aggregation Framework.
Updated May 1, 2026
Short answer
The aggregation framework is a pipeline-based system for data processing and transformation.
Deep explanation
It processes documents through stages like $match (filtering), $group (summarizing), $sort, and $project. It is the MongoDB equivalent of SQL's GROUP BY.
Real-world example
Calculating total revenue per product category for a dashboard.
Common mistakes
- Placing $group before $match, which forces the engine to process unnecessary data.
Follow-up questions
- What is the $lookup stage?