无法在nodejs+mongodb的cron作业中执行$merge聚合

const { MongoClient } = require('mongodb');
const cron = require('cron');

// 连接到MongoDB数据库
const url = 'mongodb://localhost:27017/mydatabase';
MongoClient.connect(url, (err, client) => {
  if (err) throw err;
  console.log('Connected to MongoDB');

  const db = client.db('mydatabase');
  const collection = db.collection('mycollection');

  // 创建一个cron作业，每小时执行一次
  const job = new cron.CronJob('0 * * * *', () => {
    // 执行聚合操作
    collection.aggregate([
      { $group: { _id: '$field', count: { $sum: 1 } } },
      { $merge: { into: 'mergedCollection' } }
    ]).toArray((err, result) => {
      if (err) throw err;
      console.log('Aggregation result:', result);
    });
  });

  // 启动cron作业
  job.start();
});