【发布时间】：2017-10-12 06:36:00
【问题描述】：
我提供了包含真实测试数据的 PHP 查询和数据库表。为什么 MySQL 查询执行这么慢？有什么我可以改变的来加快速度吗？执行时间约为 40 秒，表中约有 2929 条记录。
查询；
$invoice_details_query = mysqli_query($con,"SELECT i.*,
ifnull(SUM(ip.invoice_payment_amount),0) as paid,
(i.invoice_total_amount_exc_vat + i.invoice_total_vat_amount) - ifnull(SUM(ip.invoice_payment_amount),0) as due
FROM accounts_invoice i
LEFT JOIN accounts_invoice_payment ip
ON ip.invoice_payment_invoice_id = i.invoice_id
WHERE i.invoice_posted='1'
GROUP BY i.invoice_id
HAVING due>0
ORDER BY i.invoice_id ASC") or die(mysql_error());
$total = mysqli_num_rows($invoice_details_query);
数据库结构（无数据）；
-- phpMyAdmin SQL Dump
-- version 4.6.6
-- https://www.phpmyadmin.net/
--
-- Host: localhost:3306
-- Generation Time: May 12, 2017 at 09:56 PM
-- Server version: 5.6.35
-- PHP Version: 5.6.30
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8mb4 */;
--
-- Database: `propsyst_main`
--
-- --------------------------------------------------------
--
-- Table structure for table `accounts_invoice`
--
CREATE TABLE `accounts_invoice` (
`invoice_id` int(11) NOT NULL,
`invoice_token` varchar(40) COLLATE utf8_bin DEFAULT NULL,
`invoice_customer_type` tinyint(4) DEFAULT NULL,
`invoice_customer` int(11) DEFAULT NULL,
`invoice_date` date DEFAULT NULL,
`invoice_due_date` date DEFAULT NULL,
`invoice_property_id` int(11) DEFAULT NULL,
`invoice_tenancy_id` int(11) DEFAULT NULL,
`invoice_branch` int(11) DEFAULT NULL,
`invoice_payment_terms` tinyint(4) DEFAULT NULL,
`invoice_notes` text COLLATE utf8_bin,
`invoice_total_amount_exc_vat` decimal(10,2) DEFAULT NULL,
`invoice_total_vat_amount` decimal(10,2) DEFAULT NULL,
`invoice_posted` tinyint(4) DEFAULT '0',
`invoice_overdue_reminders` tinyint(4) NOT NULL DEFAULT '1',
`invoice_date_created` datetime DEFAULT NULL,
`invoice_date_updated` datetime DEFAULT NULL,
`invoice_date_posted` datetime DEFAULT NULL,
`invoice_created_by` int(11) DEFAULT NULL,
`invoice_updated_by` int(11) DEFAULT NULL,
`invoice_posted_by` int(11) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
--
-- Indexes for dumped tables
--
--
-- Indexes for table `accounts_invoice`
--
ALTER TABLE `accounts_invoice`
ADD PRIMARY KEY (`invoice_id`);
--
-- AUTO_INCREMENT for dumped tables
--
--
-- AUTO_INCREMENT for table `accounts_invoice`
--
ALTER TABLE `accounts_invoice`
MODIFY `invoice_id` int(11) NOT NULL AUTO_INCREMENT;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
解释分析；
Current selection does not contain a unique column. Grid edit, checkbox, Edit, Copy and Delete features are not available.
Your SQL query has been executed successfully.
explain accounts_invoice
invoice_id int(11) NO PRI auto_increment
invoice_token varchar(40) YES
invoice_customer_type tinyint(4) YES
invoice_customer int(11) YES
invoice_date date YES
invoice_due_date date YES
invoice_property_id int(11) YES
invoice_tenancy_id int(11) YES
invoice_branch int(11) YES
invoice_payment_terms tinyint(4) YES
invoice_notes text YES
invoice_total_amount_exc_vat decimal(10,2) YES
invoice_total_vat_amount decimal(10,2) YES
invoice_posted tinyint(4) YES 0
invoice_overdue_reminders tinyint(4) NO 1
invoice_date_created datetime YES
invoice_date_updated datetime YES
invoice_date_posted datetime YES
invoice_created_by int(11) YES
invoice_updated_by int(11) YES
invoice_posted_by int(11) YES
具有真实测试数据的数据库；
【问题讨论】：
-
您是否创建了索引？性能问题应该包括
EXPLAIN ANALYZE和一些关于表大小、索引、当前时间性能、期望时间等的信息。Slow是一个相对术语，我们需要一个真实的值来比较。 MySQL -
@JuanCarlosOropeza 我刚刚将数据库结构转储到问题中。
-
MyISAM 没有索引？这真的不是成功的秘诀。尽可能使用 InnoDB，它是一个适当的、事务性的、支持 MVCC 的数据库引擎，更易于扩展，并且可以在
WHERE或GROUP BY子句中使用的任何列上添加索引。 -
@tadman 您建议在哪些列中添加索引？
-
首先为
i.invoice_posted创建一个索引，然后为` i.invoice_id `创建另一个索引，最后在复合索引中为两者创建第三个索引。然后用 EXPLAIN PLAN 测试结果
标签： mysql sql performance