||Reshapes a document stream. $project can rename, add, or remove fields as well as create computed values and sub-documents.
||Filters the document stream, and only allows matching documents to pass into the next pipeline stage. $match uses standard MongoDB queries.
||Restricts the content of a returned document on a per-field level.
||Restricts the number of documents in an aggregation pipeline.
||Skips over a specified number of documents from the pipeline and returns the rest.
||Takes an array of documents and returns them as a stream of documents.
||Groups documents together for the purpose of calculating aggregate values based on a collection of documents.
||Takes all input documents and returns them in a stream of sorted documents.
||Returns an ordered stream of documents based on proximity to a geospatial point.
||Writes documents from the pipeline to a collection. The $out operator must be the last stage in the pipeline.