Hi! -----Original Message----- From: David Felio <[EMAIL PROTECTED]> To: Heikki Tuuri <[EMAIL PROTECTED]> Date: Tuesday, February 12, 2002 12:47 AM Subject: Re: Static or Dynamic rows -- which is faster?
>On Monday, February 11, 2002, at 12:12 PM, Heikki Tuuri wrote: > >> for InnoDB 'dynamic rows', that is, rows where you define char columns as >> VARCHAR, are faster because tables and indexes fit in smaller space. > >Is there reasoning specific to InnoDB? Dynamic tables would be smaller >regardless of the table type, I would think. In Kaj Arno's talk on >optimizing MySQL at the O'Reilly Open Source Convention last year, he said >that fixed tables are preferable and that if you must have dynamic columns, > you should try to put them in a table separate from your static columns >(slides 67 and 68 for those who have them). Has this changed? I am no expert on MyISAM, but I guess also there it is better to define VARCHAR(255) rather than CHAR(255), because in big tables disk i/o is often the bottleneck. I have understood MyISAM searches are faster if the row format is 'fixed length', but I doubt that this offsets the increased i/o. http://www.mysql.com/doc/D/y/Dynamic_format.html : " You can use OPTIMIZE table or myisamchk to defragment a table. If you have static data that you access/change a lot in the same table as some VARCHAR or BLOB columns, it might be a good idea to move the dynamic columns to other tables just to avoid fragmentation: " For InnoDB, VARCHAR is almost always better than CHAR, except in rare cases where you want to avoid fragmentation caused by updates which change a field length. >David Felio >Software Developer >Information Network of Arkansas >http://www.AccessArkansas.org Best regards, Heikki Tuuri Innobase Oy --- InnoDB - transactions, row level locking, and foreign key support for MySQL See http://www.innodb.com, download MySQL-Max from http://www.mysql.com --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
