MongoDB Query Language (MQL) Aggregation Operators
Aggregation operators are used to perform operations on grouped data in aggregation pipelines.
$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.