Aggregation Commands聚合命令

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For details on specific operator, including syntax and examples, click on the specific operator to go to its reference page.有关特定运算符的详细信息，包括语法和示例，请单击特定运算符以转到其参考页。

Aggregation Commands聚合命令

Name名称Description描述
aggregatePerforms aggregation tasks such as $group using an aggregation pipeline.使用聚合管道执行聚合任务，例如$group。
countCounts the number of documents in a collection or a view.统计集合或视图中的文档数。
distinctDisplays the distinct values found for a specified key in a collection or a view.显示在集合或视图中为指定键找到的不同值。
mapReducePerforms map-reduce aggregation for large data sets.对大型数据集执行map-reduce聚合。

Aggregation Methods聚合方法

Name名称Description描述
db.collection.aggregate()Provides access to the aggregation pipeline.提供对聚合管道的访问。
db.collection.mapReduce()Performs map-reduce aggregation for large data sets.对大型数据集执行map-reduce聚合。
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