Php MySQL中的长更新查询_Php_Mysql

Php MySQL中的长更新查询

php mysql

Php MySQL中的长更新查询,php,mysql,Php,Mysql,我必须运行一些mysql更新查询，它们需要很长时间才能运行。我使用一个PHP脚本，但每次更新需要40到600毫秒，一般在250毫秒左右我试图尽可能地优化，但脚本仍然需要30多分钟才能运行（两个表中都有20000个条目）这是我的PHP脚本和更新查询的一部分： if (mysql_num_rows($Rmaster) == 1) { //Start time $Qchange_name = 'UPDATE slave SET NewAreaName = "'.$Amaster['Area

我必须运行一些mysql更新查询，它们需要很长时间才能运行。我使用一个PHP脚本，但每次更新需要40到600毫秒，一般在250毫秒左右

我试图尽可能地优化，但脚本仍然需要30多分钟才能运行（两个表中都有20000个条目）

这是我的PHP脚本和更新查询的一部分：

if (mysql_num_rows($Rmaster) == 1) {
//Start time
    $Qchange_name = 'UPDATE slave SET NewAreaName = "'.$Amaster['AreaName'].'" WHERE Dialcode = "'.$Amain['Dialcode'].'" ORDER BY Dialcode ASC LIMIT 1 ';
    $Rchange_name = mysql_query($Qchange_name, $link);
//end time = 40 to 600ms
}

我的SELECT查询速度很快，两个表中的拨号代码都有索引

这些是我的表格（简化）：

还有什么我能让它更快的吗

PHP:5.3.4

MySQL:5.1.53

（我将在本周末首先尝试PDO解决方案并更新帖子）谢谢

更新：我用PDO尝试了以下两种不同的查询：

$Qchange_name = $pdo->prepare('UPDATE slave SET NewAreaName = ? WHERE DIalcode = ?');
$Qchange_name = $pdo->prepare('REPLACE INTO slave SET NewAreaName = ? AND Dialcode = ?');

但是仅仅做150行的foreach大约需要18秒

在我的主要循环中，我会：

$L4 = array(); // Before the loops
else if ($countQmaster1 == 1) {
   $L4[] = array($Amaster1['AreaName'], $Amain['Dialcode']);        
}

然后在循环结束时：

foreach ($L4 as $b){
    $Qchange_name->execute($b); 
}

我也有拨号代码作为主要索引

我做错什么了吗

更新：隔离查询

下面是创建表和代码的文件。我隔离了查询并减少了脚本，但运行150行仍然需要17秒

你觉得有什么不对吗？你得到同样的结果吗

PHP代码或

Mysql表下载或下载

我在考虑缓冲区问题？我在本地机器上运行，我得到一些快速和慢速更新

1 was executed in 38.87 ms 
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This script was executed in 13.45 seconds

这是配置文件：

# The MySQL server
[wampmysqld]
port        = 3306
socket      = /tmp/mysql.sock
query_cache_size=32M
# key_buffer = 16M
max_allowed_packet = 1M
table_cache = 64
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 8M

编辑：解决方案

最后，将ENGINE=InnoDB更改为MyISAM后，查询在不到3秒内执行了20000行

谢谢@JOHN的帮助！PDO帮了很多忙

您的问题可能是由于向数据库发出了>20000+1个查询而导致的

如果可能，尝试概括update语句，一次覆盖多行。因此，您可以减少查询的总数。

请注意，要进行一些优化：

使用

准备好的语句（例如，或实现）如果可能的话，总是使用，它们效率更高，可以避免sql注入等。此外，考虑使用<代码> mySqLI:/COD>扩展，<代码> mysql 被认为过时了。
还有一件事需要考虑：如何获得这些$Amaster
和Amain
值？它们是存储在脚本中还是分别为每行检索
更详细地说：
每次使用mysql\u query
执行查询时，数据库都会执行请求规划。对于影响少量行的查询，与执行本身相比，计划可能需要花费很多时间（这里没有任何统计数据，但我相信在复杂查询和短输出的情况下，这可能是数量级的倍）。因此，如果您要执行大量类似的查询，这是非常低效的，因为每个查询都要执行计划
为了避免这种情况，您应该使用准备好的语句。这背后的想法是创建一个命名对象，该对象可以缓存查询的计划并跳过计划过程，直接跳到执行步骤
在实践中，我遇到过这样一种情况：与原始sql查询（约100000条记录）相比，使用准备好的语句将执行速度提高了近百倍
DBMS中应该支持预处理语句，但据我所知，它们是
一些样品
首先，您应该在每个表中使用主键
如果您将master.DialCode更改为非空主键，它将有很大帮助
slave.DialCode也是唯一的吗？如果没有，为什么在查询中有order by和limit
当您有主键时，您可以尝试捆绑更多记录（比如100条或更多），并使用replace-into立即更新它们
REPLACE INTO slave (DialCode, NewAreaName) Values
('code1','name1'),
('code2','name2'),
('code3','name3');

首先，请分享您的更新查询，这将帮助我们指导您优化表中是否有索引，如果有，请提供这些索引的详细信息。如果您的表上没有任何索引，那就是开始的地方。@Dan Dialcode应该是索引，我在phpmyadmin中单击了索引，我得到一行：ALTERTABLE master ADDINDEX Dialcode，但它被视为键，这是同一件事吗？我在一个只有150行的新表中尝试了，但是没有帮助。我用新代码和新查询编辑了我的问题，但是仍然太慢。你尝试过禁用拨号代码的索引吗？这可能会减慢查询速度。我只是尝试将其从主控和从控中删除，但对于这样一个简单的查询，它提供了相同的时间（17秒）。请一步一步地为整个脚本计时，或者我认为您正在尝试修复未损坏的内容：）@JOHN我已经为所有代码计时，这样我发现这个查询是主要问题。我在第一条消息中提供了要测试的代码和sql表。你能检查一下有没有什么问题吗？你得到同样的结果吗？非常感谢你@我也需要数据。你能用一些记录对你的表进行SQL转储（我想150个就足够了）并把它发布到服务器上吗？
$pdo = new PDO(/*your database connection properties here*/);
$update_stmt = $pdo->prepare("UPDATE slave SET NewAreaName = ? WHERE Dialcode = ? ORDER BY Dialcode ASC LIMIT 1");

/*Iterate over $Rmaster  as you do it now{*/
    $update_stmt->execute(array($Amaster['AreaName'], $Amain['AreaCode']));
/*}*/

REPLACE INTO slave (DialCode, NewAreaName) Values
('code1','name1'),
('code2','name2'),
('code3','name3');