MongoError: Majority read concern requested, but it is not supported by the storage engine

Question

我正在使用 mlab 免费套餐，并且正在尝试在我的应用程序中使用更改流。这是我的代码：

const config = require('../globals/config');
const MongoClient = require('mongodb').MongoClient;
MongoClient.connect(config.db, {useNewUrlParser: true}, function (err, client) {
    const db = client.db('web-project-studio-db');
    // Connect using MongoClient
    var filter = [{$match: {'_id': user._id}}];

    db.collection('accounts').watch(filter).on('change', data => {
        console.log(data);
    });
});

这表示：

MongoError: Majority read concern requested, but it is not supported by the storage engine.

我应该在 mlab 设置中启用什么，还是我搞砸了什么？

Answer 1

要使用 watch，您需要使用不属于 mLab free plan 的副本集。

MongoError: Majority read concern requested, but it is not supported by the storage engine

MongoError: Majority read concern requested, but it is not supported by the storage engine

javascript

node.js

mongodb

mlab