var query = { "createdAt": { "\$lt": cutoffDate } };

  var stepStartTime = new Date();

  var originalCount = db.archivingMessageTodo.countDocuments(query);

        stepStartTime = new Date();

        const BATCH_SIZE = 10000;
        var batch = [];
        var docsBackedUp = 0;
        var cursor = db.archivingMessageTodo.find(query);

        while (cursor.hasNext()) {
            batch.push(cursor.next());
            if (batch.length === BATCH_SIZE) {
                db.archivingMessageTodoBak.insertMany(batch);
                docsBackedUp += batch.length;
                batch = [];
            }
        }

        if (batch.length > 0) {
            db.archivingMessageTodoBak.insertMany(batch);
            docsBackedUp += batch.length;
        }