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.
Continue readingIn 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.
Continue readingIn SQL Server, there are a few ways to get metadata of the result set from a query. This includes the data type of the columns returned by a T-SQL query.
In particular, the sys.dm_exec_describe_first_result_set system dynamic management function is a good choice for such a task.
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.
Continue readingIn MongoDB, the $round aggregation pipeline operator rounds a number to a whole integer or to a specified decimal place.
You have the option of specifying how many decimal places for which to round the number. To do this, pass a second argument. The first argument is the number to round, and the second (optional) argument is the number of decimal places to round it to.
Continue readingWhen using mongoimport, you can use the --jsonArray parameter to import an array of JSON documents.