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formats. In this case, use mysąldump to dump your tables before downgrading. After downgrading,

reload the dump file using mysql or mysqlimport to re-create your tables. For examples, see

Section 2.11.5, “Copying MySQL Databases to Another Machinę”.

A typical symptom of a downward-incompatible table format change when you downgrade is that you

cannot open tables. In that case, use the following procedurę:

1.    Stop the older MySQL server that you are downgrading to.

2.    Restart the newer MySQL server you are downgrading from.

3.    Dump any tables that were inaccessible to the older server by using mysqldump to create a dump

file.

4.    Stop the newer MySQL server and restart the older one.

5.    Reload the dump file into the older server. Your tables should be accessible.

If system tables in the mysql database changed, downgrading might introduce some loss of

functionality or require some adjustments. Here are some examples:

•    Trigger creation requires the TRIGGER 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 had the trigger privilege in 5.1.

•    Triggers were added in MySQL 5.0, so if you downgrade from 5.0 to 4.1, you cannot use triggers at

all

•    The mysql .proc .comment column definition changed between MySQL 5.1 and 5.5. After a

downgrade from 5.5 to 5.1, this table is seen as corrupt and in need of repair. To workaround this

problem, execute mysql_upgrade from the version of MySQL to which you downgraded.