Aggregation Pipeline

Summary

MongoDB's framework for transforming and analyzing data through a sequence of stages (`$match`, `$group`, `$sort`) — the NoSQL equivalent of complex SQL queries.

• 1Build a pipeline that groups documents and computes a sum or average.
• 2Chain `$match` and `$group` stages to filter before aggregating.
• 3Compare an aggregation pipeline to the equivalent SQL `GROUP BY` query.