In MongoDB, the $setUnion aggregation pipeline operator accepts two or more arrays and returns an array containing the elements that appear in any of those input arrays.
$setUnion accepts two or more arguments, all of which can be any valid expression as long as they each resolve to an array. $setUnion treats the arrays as sets.
In MongoDB, the $setIsSubset aggregation pipeline operator accepts two arrays and returns true when the first array is a subset of the second, and false when it isn’t.
The first array is also considered a subset when it equals the second array.
In MongoDB, the $setIntersection aggregation pipeline operator accepts two or more arrays and returns an array that contains the elements that appear in all input arrays.
$setIntersection accepts two or more arguments, all of which can be any valid expression as long as they each resolve to an array. $setIntersection treats the arrays as sets.
In MongoDB, the $setEquals aggregation pipeline operator compares two or more arrays and returns true if they have the same distinct elements and false otherwise.
$setEquals accepts two or more arguments, all of which can be any valid expression as long as they each resolve to an array. $setEquals treats the arrays as sets.
In MongoDB, the $setDifference aggregation pipeline operator accepts two sets and performs a relative complement of the second set relative to the first. It returns an array containing the elements that only exist in the first set.
$setDifference accepts two arguments, both of which can be any valid expression as long as they each resolve to an array. $setDifference treats the arrays as sets.
MongoDB offers various methods for counting the documents in a collection or view. There are also some aggregation operators that enable you to count incoming documents from a previous aggregation pipeline stage.
In MongoDB, the $sampleRate aggregation pipeline stage matches a random selection of input documents.
The number of documents selected approximates the sample rate expressed as a percentage of the total number of documents.
The $sampleRate operator was introduced in MongoDB 4.4.2.
In MongoDB, the $reverseArray aggregation pipeline operator reverses the order of items in an array.
It accepts an array expression as an argument and returns an array with the elements in reverse order.
In MongoDB, the $range aggregation pipeline operator returns a generated sequence of numbers in an array.
This sequence of numbers is based on the input values you provide.