$max - Amazon DocumentDB
Example (MongoDB Shell)Code examples
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

$max

The $max update operator updates a field's value only if the specified value is greater than the current field value. This operator is useful for maintaining maximum values across updates.

Parameters

  • field: The field to update.

  • value: The value to compare with the current field value.

Example (MongoDB Shell)

The following example demonstrates using the $max operator to update the highest recorded score for a player.

Create sample documents

db.scores.insertMany([
  { _id: 1, player: "Alice", highScore: 85 },
  { _id: 2, player: "Bob", highScore: 92 },
  { _id: 3, player: "Charlie", highScore: 78 }
])

Update example

db.scores.updateOne(
  { _id: 1 },
  { $max: { highScore: 95 } }
)

Result

The highScore field for Alice is updated to 95 because 95 is greater than the current value of 85.

{ "_id": 1, "player": "Alice", "highScore": 95 }

Code examples

To view a code example for using the $max command, choose the tab for the language that you want to use:

Node.js
const { MongoClient } = require('mongodb');

async function example() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('scores');

  const result = await collection.updateOne(
    { _id: 1 },
    { $max: { highScore: 95 } }
  );

  console.log(result);
  await client.close();
}

example();
Python
from pymongo import MongoClient

def example():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    collection = db['scores']

    result = collection.update_one(
        { '_id': 1 },
        { '$max': { 'highScore': 95 } }
    )

    print(result)
    client.close()

example()