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$min

The `$min` operator is used to retrieve the minimum value for a specified field within aggregation stages like `$group`, `$bucket`, `$bucketAuto`, or `$setWindowFields`. It's particularly useful in summarizing data or finding the smallest value in a dataset. When used as a field update operator, it updates a field only if the new value is less than the current value.

Syntax

$min: <expression>

Parameters

expressionobjectrequired

Specifies the field or computed value to determine the minimum value.

Examples

Sample Data

{
  "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
  "name": "Lakeshore Retail | DJ Equipment Stop",
  "sales": {
    "salesByCategory": [
      { "categoryName": "DJ Headphones", "totalSales": 35921 }
    ],
    "fullSales": 3700
  }
}

Using $min in $group

Calculate the minimum sales value for each category.

This query groups documents by sales category and calculates the minimum sales within each category.

Query:

db.stores.aggregate([
  { $unwind: "$sales.salesByCategory" },
  {
    $group: {
      _id: "$sales.salesByCategory.categoryName",
      minSales: {
        $min: "$sales.salesByCategory.totalSales"
      }
    }
  }
])

Output:

[
  { "_id": "Christmas Trees", "minSales": 391 },
  { "_id": "Nuts", "minSales": 257 },
  { "_id": "Camping Tables", "minSales": 171 },
  { "_id": "Music Theory Books", "minSales": 323 },
  { "_id": "Fortified Wine", "minSales": 521 }
]

Using $min in $bucket

Create buckets based on sales values and calculate the minimum sales value for each bucket.

This query creates sales buckets and finds the minimum value in each bucket.

Query:

db.stores.aggregate([
  {
    $bucket: {
      groupBy: "$sales.totalSales",
      boundaries: [0, 1000, 5000, 10000],
      default: "Other",
      output: {
        minSales: { $min: "$sales.totalSales" }
      }
    }
  }
])

Output:

[
  { "_id": 1000, "minSales": 1000 },
  { "_id": "Other", "minSales": null },
  { "_id": 0, "minSales": 108 },
  { "_id": 5000, "minSales": 5001 }
]

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