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PDO比mysql查询慢得多？

[英]PDO much slower than mysql query?

 原文  2011-06-22 20:30:41  6   2    php/ mysql/ pdo

问题描述

我在PHP中使用PDO对象来运行MYSQL查询，我一直在尝试处理查询以加快它的速度。 查询如下，如我的PHP文件中所示： 

$query = 
"SELECT SQL_NO_CACHE f.position, s.item_id, s.item_type, s.title, s.caption, s.date
FROM apiv2.search_all s 
INNER JOIN apiv2.tags t 
USING(item_id, item_type) 
LEFT JOIN apiv2.featured f 
ON t.item_id = f.item_id AND t.item_type = f.item_type AND f.feature_type = :id 
WHERE t.tag = 'FeaturedContent'
ORDER BY position IS NULL, position ASC, date";

$mysql_vars[':id'] = $id;
$stmt = $connection->prepare($query);
$stmt->execute($vars);
$data = $stmt->fetchAll(PDO::FETCH_ASSOC);

此查询的运行方式有很大不同，具体取决于我是否包含ORDER BY子句，但仅限于MYSQL控制台： 

 - MYSQL Console with ORDER BY: 1.07 sec
    - starting  0.000141
    - Opening tables    0.001416
    - System lock   0.000003
    - Table lock    0.000007
    - init  0.000021
    - checking permissions  0.000001
    - checking permissions  0.000036
    - optimizing    0.000027
    - statistics    0.000027
    - preparing 0.000015
    - Creating tmp table    0.003440
    - executing 0.000001
    - Copying to tmp table  1.050029
    - Sorting result    0.013097
    - Sending data  0.000295
    - end   0.000002
    - removing tmp table    0.002045
    - end   0.000003
    - query end 0.000002
    - freeing items 0.000331
    - logging slow query    0.000002
    - cleaning up   0.000007
 - MYSQL Console unordered output: .0053 sec
    - starting  0.000076
    - Opening tables    0.001506
    - System lock   0.000002
    - Table lock    0.000005
    - init  0.000015
    - checking permissions  0.000001
    - checking permissions  0.000022
    - optimizing    0.000012
    - statistics    0.000021
    - preparing 0.000011
    - executing 0.000001
    - Sending data  0.002895
    - end   0.000002
    - query end 0.000001
    - freeing items 0.000078
    - logging slow query    0.000000
    - cleaning up   0.000002
 - PDO Prepared stmt ORDER BY: 1.18 sec
    - 'Status' => 'starting', 'Duration' => '0.000147'
    - 'Status' => 'Opening tables', 'Duration' => '0.000784'
    - 'Status' => 'System lock', 'Duration' => '0.000004'
    - 'Status' => 'Table lock', 'Duration' => '0.000007'
    - 'Status' => 'init', 'Duration' => '0.000017'
    - 'Status' => 'checking permissions', 'Duration' => '0.000002'
    - 'Status' => 'checking permissions', 'Duration' => '0.000028'
    - 'Status' => 'optimizing', 'Duration' => '0.000018'
    - 'Status' => 'statistics', 'Duration' => '0.000026'
    - 'Status' => 'preparing', 'Duration' => '0.000014'
    - 'Status' => 'Creating tmp table', 'Duration' => '0.002112'
    - 'Status' => 'executing', 'Duration' => '0.000001'
    - 'Status' => 'Copying to tmp table', 'Duration' => '1.033056'
    - 'Status' => 'Sorting result', 'Duration' => '0.013759'
    - 'Status' => 'Sending data', 'Duration' => '0.073144'
    - 'Status' => 'end', 'Duration' => '0.000003'
    - 'Status' => 'removing tmp table', 'Duration' => '0.001999'
    - 'Status' => 'end', 'Duration' => '0.000004'
    - 'Status' => 'query end', 'Duration' => '0.000007'
    - 'Status' => 'freeing items', 'Duration' => '0.000118'
    - 'Status' => 'logging slow query', 'Duration' => '0.000001'
    - 'Status' => 'cleaning up', 'Duration' => '0.000003'
 - PDO Prepared stmt unordered output: 1.06 sec
    - 'Status' => 'starting', 'Duration' => '0.000074'
    - 'Status' => 'Opening tables', 'Duration' => '0.001364'
    - 'Status' => 'System lock', 'Duration' => '0.000004'
    - 'Status' => 'Table lock', 'Duration' => '0.000007'
    - 'Status' => 'init', 'Duration' => '0.000017'
    - 'Status' => 'checking permissions', 'Duration' => '0.000001'
    - 'Status' => 'checking permissions', 'Duration' => '0.000026'
    - 'Status' => 'optimizing', 'Duration' => '0.000015'
    - 'Status' => 'statistics', 'Duration' => '0.000027'
    - 'Status' => 'preparing', 'Duration' => '0.000013'
    - 'Status' => 'executing', 'Duration' => '0.000002'
    - 'Status' => 'Sending data', 'Duration' => '1.048216'
    - 'Status' => 'end', 'Duration' => '0.000003'
    - 'Status' => 'query end', 'Duration' => '0.000001'
    - 'Status' => 'freeing items', 'Duration' => '0.000122'
    - 'Status' => 'logging slow query', 'Duration' => '0.000001'
    - 'Status' => 'cleaning up', 'Duration' => '0.000003' 
 - MYSQL functions from PHP unordered: 1.09 sec
    - 'Status' => 'starting', 'Duration' => '0.000109'
    - 'Status' => 'checking permissions', 'Duration' => '0.000002'
    - 'Status' => 'checking permissions', 'Duration' => '0.000001'
    - 'Status' => 'checking permissions', 'Duration' => '0.000004'
    - 'Status' => 'Opening tables', 'Duration' => '0.002101'
    - 'Status' => 'System lock', 'Duration' => '0.000004'
    - 'Status' => 'Table lock', 'Duration' => '0.000009'
    - 'Status' => 'init', 'Duration' => '0.000032'
    - 'Status' => 'checking permissions', 'Duration' => '0.000003'
    - 'Status' => 'checking permissions', 'Duration' => '0.000057'
    - 'Status' => 'optimizing', 'Duration' => '0.000033'
    - 'Status' => 'statistics', 'Duration' => '0.000065'
    - 'Status' => 'preparing', 'Duration' => '0.000032'
    - 'Status' => 'executing', 'Duration' => '0.000005'
    - 'Status' => 'Sending data', 'Duration' => '1.000079'
    - 'Status' => 'end', 'Duration' => '0.000005'
    - 'Status' => 'query end', 'Duration' => '0.000002'
    - 'Status' => 'freeing items', 'Duration' => '0.000300'
    - 'Status' => 'logging slow query', 'Duration' => '0.000001'
    - 'Status' => 'cleaning up', 'Duration' => '0.000007'
 - MYSQL functions from PHP w/ ORDER BY: 1.09 sec
    - 'Status' => 'starting', 'Duration' => '0.000148'
    - 'Status' => 'checking permissions', 'Duration' => '0.000001'
    - 'Status' => 'checking permissions', 'Duration' => '0.000001'
    - 'Status' => 'checking permissions', 'Duration' => '0.000001'
    - 'Status' => 'Opening tables', 'Duration' => '0.000559'
    - 'Status' => 'System lock', 'Duration' => '0.000002'
    - 'Status' => 'Table lock', 'Duration' => '0.000006'
    - 'Status' => 'init', 'Duration' => '0.000019'
    - 'Status' => 'checking permissions', 'Duration' => '0.000001'
    - 'Status' => 'checking permissions', 'Duration' => '0.000030'
    - 'Status' => 'optimizing', 'Duration' => '0.000018'
    - 'Status' => 'statistics', 'Duration' => '0.000025'
    - 'Status' => 'preparing', 'Duration' => '0.000015'
    - 'Status' => 'Creating tmp table', 'Duration' => '0.001828'
    - 'Status' => 'executing', 'Duration' => '0.000001'
    - 'Status' => 'Copying to tmp table', 'Duration' => '0.958071'
    - 'Status' => 'Sorting result', 'Duration' => '0.013502'
    - 'Status' => 'Sending data', 'Duration' => '0.088148'
    - 'Status' => 'end', 'Duration' => '0.000003'
    - 'Status' => 'removing tmp table', 'Duration' => '0.002037'
    - 'Status' => 'end', 'Duration' => '0.000003'
    - 'Status' => 'query end', 'Duration' => '0.000001'
    - 'Status' => 'freeing items', 'Duration' => '0.000112'
    - 'Status' => 'logging slow query', 'Duration' => '0.000001'
    - 'Status' => 'cleaning up', 'Duration' => '0.000004'

解释：

与订购 

|-id-|-select_type-|-table----|-type---|-possible_keys--------|-key-----------------|-key_len-|-ref-------------------------------------|-rows--|-Extra
|-1--|-SIMPLE------|-s--------|-ALL----|-PRIMARY,search_index-|-NULL----------------|-NULL----|-NULL------------------------------------|-92166-|-Using temporary; Using filesort
|-1--|-SIMPLE------|-tags-----|-eq_ref-|-PRIMARY--------------|-PRIMARY-------------|-426-----|-apiv2.s.item_id,apiv2.s.item_type,const-|-1-----|-Using where; Using index
|-1--|-SIMPLE------|-featured-|-ref----|-type_position_index--|-type_position_index-|-62------|-const-----------------------------------|-3-----|-Using index

没有订购 

|-id-|-select_type-|-table----|-type---|-possible_keys--------|-key-----------------|-key_len-|-ref-------------------------------------|-rows--|-Extra
|-1--|-SIMPLE------|-s--------|-ALL----|-PRIMARY,search_index-|-NULL----------------|-NULL----|-NULL------------------------------------|-88346-|-
|-1--|-SIMPLE------|-tags-----|-eq_ref-|-PRIMARY--------------|-PRIMARY-------------|-426-----|-apiv2.s.item_id,apiv2.s.item_type,const-|-1-----|-Using where; Using index
|-1--|-SIMPLE------|-featured-|-ref----|-type_position_index--|-type_position_index-|-62------|-const-----------------------------------|-3-----|-Using index

表：search_all 

CREATE TABLE `search_all` (  
  `item_id` varchar(20) NOT NULL DEFAULT '',  
  `item_type` varchar(20) NOT NULL DEFAULT '',  
  `title` varchar(255) DEFAULT NULL,  
  `caption` text,  
  `date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,  
  PRIMARY KEY (`item_id`,`item_type`),  
  UNIQUE KEY `search_index` (`item_id`,`item_type`,`date`),  
  KEY `date_index` (`date`)  
) ENGINE=InnoDB DEFAULT CHARSET=utf8;  


|-id-|-select_type-|-table------|-type-|-possible_keys-|-key--|-key_len-|-ref--|-rows--|-Extra
|-1--|-SIMPLE------|-search_all-|-ALL--|-NULL----------|-NULL-|-NULL----|-NULL-|-74785-|-

表：标签 

CREATE TABLE `tags` (  
  `tag` varchar(100) NOT NULL DEFAULT '',  
  `updated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,  
  `item_id` varchar(20) NOT NULL DEFAULT '',  
  `item_type` varchar(20) NOT NULL DEFAULT '',  
  PRIMARY KEY (`item_id`,`item_type`,`tag`)  
) ENGINE=InnoDB DEFAULT CHARSET=utf8;  


|-id-|-select_type-|-table-|-type--|-possible_keys-|-key-----|-key_len-|-ref--|-rows---|-Extra
|-1--|-SIMPLE------|-tags--|-index-|-NULL----------|-PRIMARY-|-426-----|-NULL-|-197400-|-Using index

表：特色 

CREATE TABLE `featured` (  
  `position` int(10) NOT NULL DEFAULT '0',  
  `item_type` varchar(20) NOT NULL DEFAULT '',  
  `item_id` varchar(20) NOT NULL DEFAULT '',  
  `feature_type` varchar(20) NOT NULL DEFAULT '',  
  PRIMARY KEY (`position`,`item_type`,`item_id`,`feature_type`),  
  KEY `type_position_index` (`feature_type`,`position`)  
) ENGINE=InnoDB DEFAULT CHARSET=utf8;  


|-id-|-select_type-|-table----|-type--|-possible_keys-|-key-----------------|-key_len-|-ref--|-rows-|-Extra
|-1--|-SIMPLE------|-featured-|-index-|-NULL----------|-type_position_index-|-66------|-NULL-|-13---|-Using index

为什么PDO中的无序或PHP中的MSQL没有区别？ 有什么方法可以让它更快吗？

2 个解决方案

解决方案1
 5  2011-06-23 02:02:10

除非您的订单是针对索引列的，并且优化器认为使用索引是个好主意，否则“ORDER BY”将导致排序，这会为任何大小的任何结果集花费大量时间和资源。

PDO版本花费更长时间的原因是您的脚本消耗的行比SQLServer可以提供的行慢，因此数据库正在等待您的程序。 当您使用解释语言和对行结果进行大量操作的API时，这只是预期的。 这种延迟“发送数据”比排序的开销大得多（0.75秒和1.04秒）。

请注意，慢速检索由order by复杂化。 在无序SQL的情况下，行将在选择后立即发送。 在有序选择的情况下，将选择所有行，然后在发送第一个结果行之前对其进行排序。

解决方案2
 0  2011-06-23 15:21:04

您能否发布表定义（字段，字段类型等）？

我会在第一次添加一个简单的索引date表search_all和

一个简单的索引tag表tags 。

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