On Tue, Apr 29, 2008 at 5:09 AM, Charles Lambach <[EMAIL PROTECTED]> wrote: > Thank you all for your suggestions. > > So it's very important to make primary fields be as smaller as possible, > right? I'm going to change 'isbn' from VARCHAR(100) to VARCHAR(25) and, if > possible (I might change my code), from VARCHAR to BIGINT. > > By the way, which are optimal values for "key_len" parameter when doing > EXPLAIN? > > Regards, > --Charles > "The key_len column indicates the length of the key that MySQL decided to use. The length is NULL if the key column says NULL. Note that the value of key_len enables you to determine how many parts of a multiple-part key MySQL actually uses." http://dev.mysql.com/doc/refman/5.0/en/using-explain.html
Note: that is length in bytes. I don't know how much faster your queries will get by reducing the varchar size, I have not had to deal with many performance issues of this type. If it is effective (you are noting query times, right?) you should be able to further reduce the size by change the character set from multi-btye utf-8 to single byte ascii. The query would be something like: ALTER TABLE `books` CHANGE `isbn` `isbn` VARCHAR( 25) CHARACTER SET ascii NOT NULL -- Rob Wultsch [EMAIL PROTECTED] wultsch (aim) -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
