skip-name-resolve

?

現象：

Windows 2003下的MySQL 5服務器，本機連接到MySQL服務非?？?，局域網內有兩臺Linux機器，有一臺連接很快，另外一臺輸入密碼后要等好幾秒鐘才能連上。

解決辦法：

在MySQL服務器的配置中增加一個如下配置后速度飛快。

[mysqld]
skip-name-resolve

附錄：( 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 lookop 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

遠程連接MySQL速度慢的解決辦法