Single-purpose aggregation operators are available so that you can operate on a collection or a cursor. The following table summarizes the operators which can operate on a collection:
| db.collection.count() | Wraps the $count aggregation operator to produce the number of documents in a collection. |
| db.collection.distinct() |
Wrapper for the distinct command (https://docs.mongodb.com/manual/reference/command/distinct/#distinct). Produces distinct values for document fields across a collection. |
The following table summarizes single-purpose aggregation operations which can be performed on a cursor (such as the iteration returned after executing db.collection.find()):
| cursor.count() | Equivalent to db.collection.count() ... |
