我使用node-mongodb-native驱动与MongoDB写一个网站。

我有一些关于如何管理连接的问题:

Is it enough using only one MongoDB connection for all requests? Are there any performance issues? If not, can I setup a global connection to use in the whole application? If not, is it good if I open a new connection when request arrives, and close it when handled the request? Is it expensive to open and close a connection? Should I use a global connection pool? I hear the driver has a native connection pool. Is it a good choice? If I use a connection pool, how many connections should be used? Are there other things I should notice?


当前回答

如果你有Express.js,你可以使用express- MongoDB -db在请求之间缓存和共享MongoDB连接,而不需要一个池(因为接受的答案说这是共享连接的正确方式)。

如果没有,你可以查看它的源代码并在另一个框架中使用它。

其他回答

您应该将连接创建为服务,然后在需要时重用它。

// db.service.js
import { MongoClient } from "mongodb";
import database from "../config/database";

const dbService = {
  db: undefined,
  connect: callback => {
    MongoClient.connect(database.uri, function(err, data) {
      if (err) {
        MongoClient.close();
        callback(err);
      }
      dbService.db = data;
      console.log("Connected to database");
      callback(null);
    });
  }
};

export default dbService;

我的App.js样本

// App Start
dbService.connect(err => {
  if (err) {
    console.log("Error: ", err);
    process.exit(1);
  }

  server.listen(config.port, () => {
    console.log(`Api runnning at ${config.port}`);
  });
});

想用就用吧

import dbService from "db.service.js"
const db = dbService.db

使用下面的方法,您可以轻松地管理尽可能多的连接

var mongoose = require('mongoose');


//Set up default mongoose connection
const bankDB = ()=>{
    return  mongoose.createConnection('mongodb+srv://<username>:<passwprd>@mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
    
}

bankDB().then(()=>console.log('Connected to mongoDB-Atlas bankApp...'))
       .catch((err)=>console.error('Could not connected to mongoDB',err));
       
//Set up second mongoose connection
const myDB = ()=>{
    return  mongoose.createConnection('mongodb+srv://<username>:<password>@mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
   
}
myDB().then(()=>console.log('Connected to mongoDB-Atlas connection 2...'))
       .catch((err)=>console.error('Could not connected to mongoDB',err));

module.exports = { bankDB(), myDB() };

我一直在我的应用程序中使用redis连接的通用池-我强烈推荐它。它是通用的,我肯定知道它适用于mysql,所以我不认为你会有任何问题与它和mongo

https://github.com/coopernurse/node-pool

node-mongodb-native的主提交者说:

打开MongoClient。连接一次,当你的应用程序启动和重用 db对象。每个.connect并不是一个单独的连接池 创建一个新的连接池。

因此,为了直接回答您的问题,重用MongoClient.connect()生成的db对象。这为您提供了池化,与在每个db操作上打开/关闭连接相比,将提供显著的速度提高。

我已经在我的项目中实现了下面的代码,在我的代码中实现连接池,这样它将在我的项目中创建一个最小的连接,并重用可用的连接

/* Mongo.js*/

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/yourdatabasename"; 
var assert = require('assert');

var connection=[];
// Create the database connection
establishConnection = function(callback){

                MongoClient.connect(url, { poolSize: 10 },function(err, db) {
                    assert.equal(null, err);

                        connection = db
                        if(typeof callback === 'function' && callback())
                            callback(connection)

                    }

                )



}

function getconnection(){
    return connection
}

module.exports = {

    establishConnection:establishConnection,
    getconnection:getconnection
}

/*app.js*/
// establish one connection with all other routes will use.
var db = require('./routes/mongo')

db.establishConnection();

//you can also call with callback if you wanna create any collection at starting
/*
db.establishConnection(function(conn){
  conn.createCollection("collectionName", function(err, res) {
    if (err) throw err;
    console.log("Collection created!");
  });
};
*/

// anyother route.js

var db = require('./mongo')

router.get('/', function(req, res, next) {
    var connection = db.getconnection()
    res.send("Hello");

});