Eric, for InnoDB 'dynamic rows', that is, rows where you define char columns as VARCHAR, are faster because tables and indexes fit in smaller space.
Only in some rare cases where you want to avoid fragmentation caused by updates which change a column length, a fixed-length CHAR(...) column can be a better option. I guess also for MyISAM dynamic rows are usually faster, because you win in smaller disk i/o. 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 "Eric Mayers" wrote in message ... >I have a large data set (15 mil rows) consisting of a datetime column >and a char(255) column. I seem to recall seeing something about >performance benefits for using static length rows with MyISAM tables, >and I've heard some argument for using dynamic length rows (e.g., use >varchar rather than char) in InnoDB tables. So for performance sake >(assuming no index can be used), which is better for these table types? > > >I can imagine that using dynamic length would be better in the case of >an IO bottleneck, but maybe there is an efficiency gain from knowing >where the records start and stop ahead of time..? > >Thanks, >Eric > >uugh. sql. --------------------------------------------------------------------- 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 --------------------------------------------------------------------- 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
