持续打开MongoDB数据库连接 [英] Keeping open a MongoDB database connection

问题描述

在使用MongoDB的许多入门示例中，您将看到类似以下的代码:

In so many introductory examples of using MongoDB, you see code like this:

var MongoClient = require('mongodb').MongoClient;
MongoClient.connect("mongodb://localhost:port/adatabase", function(err, db)
{
    /* Some operation... CRUD, etc. */
    db.close();
});

如果MongoDB与其他任何数据库系统一样，open和close操作通常在时间上很昂贵.

If MongoDB is like any other database system, open and close operations are typically expensive time-wise.

所以，我的问题是:只需简单地执行一次MongoClient.connect("...，将返回的db值分配给全局某个模块，就可以了，模块中的各种功能可以完成各种与数据库相关的工作(将文档插入到集合，更新文档等)，然后由应用程序的其他部分调用它们(从而重新使用该db值)，然后在应用程序完成后才执行close .

So, my question is this: Is it OK to simply do the MongoClient.connect("... once, assign the returned db value to some module global, have various functions in the module do various database-related work (insert documents into collections, update documents, etc. etc.) when they're called by other parts of the application (and thereby re-use that db value), and then, when the application is done, only then do the close.

换句话说，open和close仅执行一次-并非每次您都需要进行一些与数据库相关的操作时.而且，当实际完成所有与数据库有关的工作时，您将继续使用在最初的open\connect中返回的db对象，直到最后将其与close一起使用.

In other words, open and close are done once - not every time you need to go and do some database-related operation. And you keep re-using that db object that was returned during the initial open\connect, only to dispose of it at the end, with the close, when you're actually done with all your database-related work.

很明显，由于所有I/O都是异步的，因此在发布close之前，您要确保最后一个数据库操作已完成.似乎这样应该可以，但我想仔细检查一下，以防万一我刚接触MongoDB时遗漏了一些东西.谢谢！

Obviously, since all the I/O is asynch, before the close you'd make sure that the last database operation completed before issuing the close. Seems like this should be OK, but i wanted to double-check just in case I'm missing something as I'm new to MongoDB. Thanks!

推荐答案

是的，这是正常的行为.启动您的应用程序，连接到数据库，对数据库进行长时间的操作，如果连接意外中断，则可能重新连接，然后再也不要关闭连接(仅依赖于进程终止时发生的自动关闭)

Yes, that is fine and typical behavior. start your app, connect to db, do operations against the db for a long time, maybe re-connect if the connection ever dies unexpectedly, and then just never close the connection (just rely on the automatic close that happens when your process dies).

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