Readers of PlanetMySQL may have recently noticed some posts on tuning MySQL server performance in five minutes or even in three minutes, I’d like to take things in the opposite direction, showing you how to tune performance in two to four days.

Actually I should say you can learn to tune performance in two to four days, tuning itself actually takes a long time and is a continuing process because things change constantly. I’m not talking about performance tuning in the ‘limit resource usage so the server does not crash’ sense that you see in limiting connections, but in the sense of getting the most from your server, making specific changes and measuring the results. Remember folks, if you don’t benchmark you have no idea if your changes have improved your situation or actually made it worse. Do you want to know if your server can handle a traffic spike? Better to simulate one ahead of time than find out the hard way.

So …

This summer, C++ gone wild. These are brilliant:

int Log_event::read_log_event(IO_CACHE* file, String* packet,
                              pthread_mutex_t* log_lock)

and

#ifndef MYSQL_CLIENT
Log_event* Log_event::read_log_event(IO_CACHE* file,
                                     pthread_mutex_t* log_lock,
                                     bool old_format)
#else
Log_event* Log_event::read_log_event(IO_CACHE* file, bool old_format)
#endif

and

Log_event* Log_event::read_log_event(const char* buf, int event_len,
                                     const char **error, bool old_format)
        

Save me.

It seems to me that a lot of people have auth denial when trying to make connections to MySQL. They seem to ignore the text of the error message. ‘Access Denied’ means access denied, nothing else.

Remember three things have to match. The host as MySQL sees it, the username, and the password. When MySQL returns access denied it’s not broken. One or more of those three things does not match. I don’t really need to reiterate what’s in the manual. Chang the lock or change the key to make it fit.