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$min (Expression)

Definition

$min

Returns the minimum value from an array.

Note

Disambiguation

This page describes $min when used as an expression.

You can also use $min in these other contexts:

$min (accumulator), used in grouping to return the minimum value from a group of documents.
$min (window function), used in the $setWindowFields stage to return the minimum value from documents in a particular window.

Syntax

{ $min: <expression> }

The expression must evaluate to an array.

Behavior

Result Type

When $min compares values of different types, it uses the BSON comparison order to determine which value is smaller.

Null or Missing Values

If some, but not all, input values are null or missing, $min considers only the non-null and non-missing values.

If all input values are null or missing, $min returns null.

Example

The examples on this page use data from the sample_mflix dataset. For details on how to load this dataset into your self-managed MongoDB deployment, see Load the Sample Dataset. If you made any modifications to the sample databases, you may need to drop and recreate the databases to run the examples on this page.

The following example uses $min in the $project stage to calculate the minimum values from the sample_mflix.movies collection.

db.movies.aggregate( [
   {
      $match: {
         title: {
            $in: [
               "The Godfather",
               "Inception",
               "The Dark Knight"
            ]
         }
      }
   },
   {
      $project: {
         _id: 0,
         title: 1,
         firstAlphabeticalGenre: { $min: "$genres" },
         lowestRating: {
            $min: [ { $multiply: [ "$imdb.rating", 10 ] }, "$metacritic" ]
         }
      }
   },
   {
      $sort: { title: 1 }
   }
] )

[
  {
    title: 'Inception',
    firstAlphabeticalGenre: 'Action',
    lowestRating: 74
  },
  {
    title: 'The Dark Knight',
    firstAlphabeticalGenre: 'Action',
    lowestRating: 82
  },
  {
    title: 'The Godfather',
    firstAlphabeticalGenre: 'Crime',
    lowestRating: 92
  }
]

The preceding pipeline:

Uses $match to filter for three specific movies.
Uses $project with $min to create two fields:
- firstAlphabeticalGenre: First genre in alphabetical order from the genres array, using { $min: "$genres" }
- lowestRating: Lowest rating between IMDb and Metacritic, both normalized to a 0–100 scale, using { $min: [ { $multiply: [ "$imdb.rating", 10 ] }, "$metacritic" ] }
Uses $sort to sort results by title.

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$median

$minN-array-element