Get maximum and minimum value in MongoDB?

To get the maximum and minimum values from a collection in MongoDB, use the $max and $min aggregation operators within a $group stage. This approach efficiently processes all documents to find the extreme values in a specified field.

Syntax

db.collection.aggregate([
    {
        $group: {
            _id: null,
            MaximumValue: { $max: "$fieldName" },
            MinimumValue: { $min: "$fieldName" }
        }
    }
]);

Sample Data

db.maxAndMinDemo.insertMany([
    { "Value": 98 },
    { "Value": 97 },
    { "Value": 69 },
    { "Value": 96 },
    { "Value": 99 }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cd698a357806ebf1256f129"),
        ObjectId("5cd698af57806ebf1256f12a"),
        ObjectId("5cd698b357806ebf1256f12b"),
        ObjectId("5cd698b657806ebf1256f12c"),
        ObjectId("5cd698b957806ebf1256f12d")
    ]
}

Display all documents in the collection ?

db.maxAndMinDemo.find().pretty();

{ "_id": ObjectId("5cd698a357806ebf1256f129"), "Value": 98 }
{ "_id": ObjectId("5cd698af57806ebf1256f12a"), "Value": 97 }
{ "_id": ObjectId("5cd698b357806ebf1256f12b"), "Value": 69 }
{ "_id": ObjectId("5cd698b657806ebf1256f12c"), "Value": 96 }
{ "_id": ObjectId("5cd698b957806ebf1256f12d"), "Value": 99 }

Example

Find the maximum and minimum values in the "Value" field ?

db.maxAndMinDemo.aggregate([
    {
        $group: {
            _id: null,
            MaximumValue: { $max: "$Value" },
            MinimumValue: { $min: "$Value" }
        }
    }
]);

{ "_id": null, "MaximumValue": 99, "MinimumValue": 69 }

Key Points

• Set _id: null to group all documents together for collection−wide calculations.
• $max and $min operators work with numeric, date, and string values.
• Use $fieldName syntax to reference the field containing values to compare.

Conclusion

The aggregation framework with $max and $min operators provides an efficient way to find extreme values in MongoDB collections. Group all documents with _id: null to calculate collection−wide maximum and minimum values.