Databases · Middle · Question 49 of 75

What is MongoDB's aggregation pipeline?

1A replication mechanism
✓Correct answer: A sequence of stages ($match, $group, $lookup, $sort, ...) that transform documents, similar to SQL's GROUP BY and joins
3A tool for importing CSV files

Explanation

Put $match early so indexes can be used and fewer documents flow through later stages.

Further reading

MongoDB: Aggregation pipeline ↗

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