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Aggregation Reference

Aggregation Pipeline Quick Reference
Quick reference card for aggregation pipeline.
Aggregation Pipeline Operators
Aggregation pipeline operations have a collection of operators available to define and manipulate documents in pipeline stages.
Aggregation Commands Comparison
A comparison of group, mapReduce and aggregate that explores the strengths and limitations of each aggregation modality.
SQL to Aggregation Mapping Chart
An overview common aggregation operations in SQL and MongoDB using the aggregation pipeline and operators in MongoDB and common SQL statements.
Aggregation Commands
The reference for the data aggregation commands, which provide the interfaces to MongoDB’s aggregation capability.
Variables in Aggregation Expressions
Use of variables in aggregation pipeline expressions.