Aggregation - operators

Aggregation operators are used to perform operations on grouped data in aggregation pipelines.

	Description
$addFields	The $addFields stage in the aggregation pipeline is used to add new fields to documents.
$bucket	The $bucket operator groups input documents into buckets based on specified boundaries.
$changeStream	The $changeStream stage opens a change stream cursor to track data changes in real-time.
$collStats	The $collStats stage in the aggregation pipeline is used to return statistics about a collection.
$convert	The $convert operator converts an expression into the specified type
$densify	The $densify operator adds missing data points in a sequence of values within an array or collection.
$documents	The $documents stage creates a pipeline from a set of provided documents.
$facet	The $facet allows for multiple parallel aggregations to be executed within a single pipeline stage.
$fill	The $fill stage allows filling missing values in documents based on specified methods and criteria.
$geoNear	The $geoNear operator finds and sorts documents by their proximity to a geospatial point, returning distance information for each document.
$group	The $group stage groups documents by specified identifier expressions and applies accumulator expressions.
$indexStats	The $indexStats stage returns usage statistics for each index in the collection.
$isNumber	The $isNumber operator checks if a specified expression is a numerical type
$lookup	The $lookup stage in the Aggregation Framework is used to perform left outer joins with other collections.
$match	The $match stage in the aggregation pipeline is used to filter documents that match a specified condition.
$merge	The $merge stage in an aggregation pipeline writes the results of the aggregation to a specified collection.
$out	The $out stage in an aggregation pipeline writes the resulting documents to a specified collection.
$redact	The $redact operator filters the content of the documents based on access rights.
$replaceWith	The $replaceWith operator in DocumentDB returns a document after replacing a document with the specified document
$sample	The $sample operator in DocumentDB returns a randomly selected number of documents
$set	The $set operator in DocumentDB updates or creates a new field with a specified value
$skip	The $skip stage in the aggregation pipeline is used to skip a specified number of documents from the input and pass the remaining documents to the next stage in the pipeline.
$sort	The $sort stage in the aggregation pipeline is used to order the documents in the pipeline by a specified field or fields.
$sortByCount	The $sortByCount stage in the aggregation pipeline is used to group documents by a specified expression and then sort the count of documents in each group in descending order.
$toBool	The $toBool operator converts an expression into a Boolean type
$toDate	The $toDate operator converts supported types to a proper Date object.
$toDecimal	The $toDecimal operator converts an expression into a Decimal type
$toDouble	The $toDouble operator converts an expression into a Double value
$toInt	The $toInt operator converts an expression into an Integer
$toLong	The $toLong operator converts an expression into a Long value
$toObjectId	The $toObjectId operator converts an expression into an ObjectId
$toString	The $toString operator converts an expression into a String
$unset	The $unset stage in the aggregation pipeline is used to remove specified fields from documents.
$unwind	The $unwind stage in the aggregation framework is used to deconstruct an array field from the input documents to output a document for each element.