MySQL Upgrade Webinar Questions Followup

I did a Webinar about MySQL Upgrade – Best Practices Yesterday and there were some questions we could not answer during Webinar, following Jay’s Lead I decided to post them as a Blog Post.

Q: Can you go directly MySQL 5.0 to 5.5 for MyISAM tables?
MyISAM have not been getting any significant development since MySQL 4.1, so in-place upgrade of MySQL 5.0 to MySQL 5.5 should be rather safe from data standpoint. There are still possibilities for sorting order and data type related changes, so you still need to run mysql_upgrade to check if any tables need to be rebuilt for new versions. Note this only applies to the data part of upgrade, you still need to keep into account possible query changes, replication etc.