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Aggregation Commands

注解

For details on specific operator, including syntax and examples, click on the specific operator to go to its reference page.

Aggregation Commands

Name Description
aggregate Performs aggregation tasks such as group using the aggregation framework.
count Counts the number of documents in a collection.
distinct Displays the distinct values found for a specified key in a collection.
group Deprecated. Groups documents in a collection by the specified key and performs simple aggregation.
mapReduce Performs map-reduce aggregation for large data sets.

Aggregation Methods

Name Description
db.collection.aggregate() Provides access to the aggregation pipeline.
db.collection.group() Deprecated. Groups documents in a collection by the specified key and performs simple aggregation.
db.collection.mapReduce() Performs map-reduce aggregation for large data sets.