When downgrading to MySQL 5.0 from MySQL 5.1, you should keep in mind the following issues relating to features found in MySQL 5.1, but not in MySQL 5.0:
Partitioning. MySQL 5.0 does not support user-defined partitioning. If a table was created as a partitioned table in 5.1 (or if an table created in a previous version of MySQL was altered to include partitions after an upgrade to 5.1), the table is accessible after downgrade only if you do one of the following:
Export the table using mysqldump and then drop it in MySQL 5.1; import the table again following the downgrade to MySQL 5.0.
Prior to the downgrade, remove the table's partitioning
MySQL 5.0 does not support scheduled events. If your
databases contain scheduled event definitions, you should
prevent them from being dumped when you use
mysqldump by using the
option. (See Section 4.5.4, “mysqldump — A Database Backup Program”.)
MySQL 5.1.21 added a number of new columns to the
mysql.proc table in which stored
routine definitions are stored. If you are downgrading
from MySQL 5.1.21 or later to MySQL 5.0, you cannot import
the MySQL 5.1 routine definitions into MySQL 5.0.46 or
earlier using the dump of
created by mysqldump (such as when
Instead, you should run mysqldump
prior to performing the downgrade and run the stored
routines DDL statements following the downgrade.
See Bug #11986, Bug #30029, and Bug #30660, for more information.
Trigger creation requires the
privilege as of MySQL 5.1. In MySQL 5.0, there is no
TRIGGER privilege and
SUPER is required instead. If you
downgrade from MySQL 5.1 to 5.0, you will need to give the
SUPER privilege to those accounts that
TRIGGER privilege in 5.1.