• How to define memory limit in my.cnf :
    select @@key_buffer_size + @@query_cache_size + ((@@read_buffer_size + @@sort_buffer_size + @@join_buffer_size) * @@max_connections);
  • Hint do a show status and check if you have Threads_cached != 0 is ok otherwise you need to increase your thread_cache vars in my.cnf.( in mySQL > 4 you can do : show status like 'Thread%'; )
  • In your mysql command line you can choose the display add in your .bashrc : 
    export MYSQL_PS1="\u@\h \d>"
  • How to re-create the mysql index file ( MYI ) do a flush table before, and : repair table tablename USE_FRM