云服务器安装mysql访问速度特别慢

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我在阿里云主机上使用宝塔安装了MySQL,在主机访问速度没有问题,但是我在远程本地访问时,连接打开数据库特别慢。

但是程序的数据库连接池使用时,一旦连接建立使用上就没有问题了。


解决方法:在配置文件my.cnf的[mysqld]下加入

skip-name-resolve

说明和提示:

原因是默认安装的MySql开启了DNS的反向解析。如果禁用的话就不能在MySQL的授权表中使用主机名了而只能用ip格式。


How MySQL uses DNS

When a new thread connects to mysqld, mysqld will spawn a new thread to handle the request. This thread will first check if the hostname is in the hostname cache. If not the thread will call gethostbyaddr_r() and gethostbyname_r() to resolve the hostname.


If the operating system doesn’t support the above thread-safe calls, the thread will lock a mutex and call gethostbyaddr() and gethostbyname() instead. Note that in this case no other thread can resolve other hostnames that is not in the hostname cache until the first thread is ready.


You can disable DNS host lookup by starting mysqld with –skip-name-resolve. In this case you can however only use IP names in the MySQL privilege tables.


If you have a very slow DNS and many hosts, you can get more performance by either disabling DNS lookup with –skip-name-resolve or by increasing the HOST_CACHE_SIZE define (default: 128) and recompile mysqld.


You can disable the hostname cache with –skip-host-cache. You can clear the hostname cache with FLUSH HOSTS or mysqladmin flush-hosts.


If you don’t want to allow connections over TCP/IP, you can do this by starting mysqld with –skip-networking.


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