For details on specific commands, including syntax and examples, click on the specific command to go to its reference page.
||Performs aggregation tasks such as group using the aggregation framework.|
||Counts the number of documents in a collection.|
||Displays the distinct values found for a specified key in a collection.|
||Deprecated. Groups documents in a collection by the specified key and performs simple aggregation.|
||Performs map-reduce aggregation for large data sets.|
For a detailed comparison of the different approaches, see Aggregation Commands Comparison.