为什么使用Mysql本机驱动程序为Nodejs执行相同的查询需要大约300毫秒,即使使用或不使用“创建池”选项?
请参阅下面附带截图中的突出显示部分
同样对于本机驱动程序执行时间,请参见下面附带的屏幕截
node.js的代码库Mysql Native驱动程序
db.js
var mysql = require('mysql');
var connectionpool = mysql.createPool({
connectionLimit: 100, //important
host: 'localhost',
user: config.development.username,
password: config.development.password,
database: config.development.database,
multipleStatements: true,
});
exports.getConnection = function(callback) {
connectionpool.getConnection(callback);
};
emp.js
var connections = require('../config/db');
var pre_query = new Date().getTime();
var sqlstatements = "select * from employees where recordstate<>'raw'and DATE(createdAt) " + "between ('1982-03-24') and ('2017-04-23') order by employeesID desc limit 20 offset 0;" + "select COUNT(*) as count from employees where recordstate<>'raw'and " + "DATE(createdAt) between ('1982-03-24') and ('2017-04-23') order by employeesID desc";
connections.getConnection(function(err, c) {
console.log(sqlstatements)
c.query(sqlstatements, function(err, projects) {
console.log(err);
if (!err) {
c.release();
var red = new Object();
red.rows = JSON.parse(JSON.stringify(projects[0]));
red.count = JSON.parse(JSON.stringify(projects[1]))[0].count;
var post_query = new Date().getTime();
// calculate the duration in seconds
var duration = (post_query - pre_query) / 1000;
console.log(duration)
// console.log(red);
res.json(red);
}
})
})
最佳答案 您在JS中的测量包括连接设置和结果的所有处理. MySQL Workbench(和MySQL终端客户端)中报告的时间只是服务器报告的内容(运行查询和结果传输).连接设置可能需要300ms的大部分时间.尝试在运行实际查询之前将pre_query init移动到该行.并在此之后直接结束时间测量(在console.log(错误)调用之前.这提供了与其他客户端工具报告的结果相当的结果.