mysql表列复制,mysql连接时间和内存控制。
有两个表临时表temp_t,和正表table1,都是MyISAM,分别有28W条左右的记录。
cron定时每分钟从网络上获取一些信息,先存储到temp_t(频繁写入),
然后cron定时每10分钟从temp_t复制信息到正表table1(频繁读取,每10分钟写一次)。
temp_t字段 id(auto_increment),title(varchar(200)),content(varchar(500)),date(DATETIME), mykey(tinyint(1) Default 1, 这个来判别是否已经复制到正表,复制过后UPDATE为2)
table1字段 id(没有auto_increment),title(varchar(200)),content(varchar(500)),date(DATETIME)
28W记录,每个数据表大概有300MB,每次更新差不多要2K-3K条记录。
如果直接复制的话,MYSQL连接时间过长,导致MYSQL性能下降table1会出现类似于锁表的现象,查询table1的时间明显加长
require dirname(__FILE__) . '/../connection.php';<br /> mysql_select_db("news",$connextion);<br /> mysql_query("SET NAMES utf8");<br /> $query = mysql_query("SELECT * FROM temp_t where mykey = '1'");<br /> while($rows = mysql_fetch_array($query)){<br /> mysql_query("UPDATE temp_t SET mykey='2' WHERE id='".mysql_real_escape_string($rows['id'])."'");<br /> mysql_query("INSERT INTO table1 (id,title,content,date) values ('".mysql_real_escape_string($rows['id'])."','".mysql_real_escape_string($rows['title'])."','".mysql_real_escape_string($rows['content'])."','".mysql_real_escape_string($rows['date'])."'");<br /> }<br /> mysql_close($connextion);
于是想先把记录从temp_t里的数据先读出来,存为一个json数组,然后再复制数据到table1,但是有时会遇到Cannot allocate memory,然后导致整个服务器崩溃(是不是这个json数组太大,占了巨量的内存)。PS:已经在php.ini里将memory limit加到64M了(但总觉得治标不治本,这么一个复制过程,不需要那么多内存,关键还是代码不合理)。
require dirname(__FILE__) . '/../connection.php';<br /> mysql_select_db("news",$connextion);<br /> mysql_query("SET NAMES utf8");<br /> $query = mysql_query("SELECT * FROM temp_t where mykey = '1'");<br /> $jon = array();<br /> while($rows = mysql_fetch_array($query)){<br /> $jon['a'] = $rows['id'];<br /> $jon['b'] = $rows['title'];<br /> $jon['c'] = $rows['content'];<br /> $jon['d'] = $rows['date'];<br /> $pjon .= json_encode($jon).',';<br /> }<br /> mysql_close($connextion);<br /> $njso = json_decode('['.substr($pjon,0,-1).']');<br /> foreach($njso as $nx){ <br /> if($nx->a){<br /> require dirname(__FILE__) . '/../connection.php';<br /> mysql_select_db("news",$connextion);<br /> mysql_query("SET NAMES utf8");<br /> mysql_query("UPDATE temp_t SET mykey='2' WHERE id='".mysql_real_escape_string($nx->a)."'");<br /> mysql_query("INSERT INTO table1 (id,title,content,date) values ('".mysql_real_escape_string($nx->a)."','".mysql_real_escape_string($nx->b)."','".mysql_real_escape_string($nx->c)."','".mysql_real_escape_string($nx->d)."'");<br /> mysql_close($connextion);<br /> }<br /> }
所以求助大虾们,有没有更节省的代码用来复制表的信息?要求mysql连接时间短,内存消耗又少?谢谢大家。

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.

In PHP, use the clone keyword to create a copy of the object and customize the cloning behavior through the \_\_clone magic method. 1. Use the clone keyword to make a shallow copy, cloning the object's properties but not the object's properties. 2. The \_\_clone method can deeply copy nested objects to avoid shallow copying problems. 3. Pay attention to avoid circular references and performance problems in cloning, and optimize cloning operations to improve efficiency.

PHP is suitable for web development and content management systems, and Python is suitable for data science, machine learning and automation scripts. 1.PHP performs well in building fast and scalable websites and applications and is commonly used in CMS such as WordPress. 2. Python has performed outstandingly in the fields of data science and machine learning, with rich libraries such as NumPy and TensorFlow.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Atom editor mac version download
The most popular open source editor

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use