Node.js-监视数据库中的更改 [英] Node.js - Monitoring a database for changes

问题描述

我正在使用node.js服务器在我的Web应用程序和数据库之间创建一个接近实时"的套接字.当前，我正在使用MySQL，它每秒在节点中轮询一次，以检查表是否有任何更改(基于时间戳).

I am using a node.js server to create a 'close to real-time' socket between my web app and a database. Currently I am using MySQL which I am polling every second in node to check if there are any changes to the table (based on a timestamp.)

我想知道是否有使用MySQL进行类似操作的特定技术?目前，我只是在运行SQL查询并在下一次民意调查之前使用setTimeout.

I was wondering if there any specific techniques to doing something like this with MySQL? At the moment, I am just running a SQL query and using setTimeout before the next poll.

我知道在这样的实例中使用NoSQL数据库更为普遍，但是我对这项技术并不满意，我宁愿使用SQL.

I know it's more common to use a NoSQL database in instances like this but I'm not really comfortable with the technology and I'd much rather use SQL.

有人对使用node监视SQL数据库有任何经验或技巧吗?

Does anyone have any experience or tips for monitoring a SQL database with node?

推荐答案

我个人不会为此使用轮询机制.我认为这是pub/sub mq作为数据库顶部组件的一个很好的用例，允许消费者订阅特定渠道以关注他们关心的实体上的更改事件.

I wouldn't personally use a polling mechanism for this. I think this is a pretty good use case for a pub/sub mq as a component on top of the database that allows consumers to subscribe to specific channels for change events on entities that they care about.

例如:

1. 有人要求更改模型
2. 模型广播更改事件
3. 排队更改以将其保留在数据库中
4. 触发消息队列中特定频道上的更改集，以分发给所有相关方

您可以使用节点EventEmitter对此类事物使用非常简单的进程内发布/订阅机制，并且在需要扩展，具有持久性要求或需要跨语言MQ时，您可以使用Rabbitmq这样的技术， zeromq等.我已经开始在我的一个应用程序中实现非常轻巧的功能: https://github.com/jmoyers/mettle/blob/master/src/pubsub.coffee

You can use a very simple in process pub/sub mechanism for this type of thing using nodes EventEmitter, and as you need to scale, have durability requirements, or need a cross language MQ you can go to a technology like rabbitmq, zeromq, etc. I've started to implement something very lightweight to do just this in one of my applications: https://github.com/jmoyers/mettle/blob/master/src/pubsub.coffee

它归结为:

pubsub.sub('users.*', function(updates){
    // Interested party handles updates for user objects
});

那样，您就不会对数据库施加愚蠢的轮询压力.实际上，变更分布完全独立于写入数据库

That way you aren't putting stupid polling pressure on your database. In fact, change distribution is completely independent of writing to your database

乔什

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