If you upgrade to MariaDB 5.1 from MySQL 5.1 you don't have to do anything with your data or MySQL clients. Things should "just work".

When upgrading between different major versions of MariaDB or MySQL you need to run the mysql_upgrade program to convert data that are incompatible between versions. This will also update your privilege tables in the mysql database to the latest format.

In almost all cases mysql_upgrade should be able to convert your tables, without you having to dump and restore your data.

After installing MariaDB, just do:

mysql_upgrade --verbose

If you want to run with a specific TCP/IP port do:

mysql_upgrade --host=127.0.0.1 --port=3308 --protocol=tcp

If you want to connect with a socket do:

mysql_upgrade --socket=127.0.0.1 --protocol=socket

To see other options, use --help.

"mysql_upgrade" reads the my.cnf sections [mysql_upgrade] and [client] for default values.

There are a variety of reasons tables need to be converted; they could be any of the following:

• The collation (sorting order) for an index column has changed
• A field type has changed storage format
  • DECIMAL and VARCHAR changed format between MySQL 4.1 and MySQL 5.0
• An engine has a new storage format
  • ARCHIVE changed storage format between 5.0 and 5.1
• The format for storing table names has changed
  • In MySQL 5.1 table names are encoded so that the file names are identical on all computers. Old table names that contains forbidden file name characters will show up prefixed with #mysql50# in SHOW TABLES until you convert them.

If you don't convert the tables, one of the following things may happen:

• You will get warnings in the error log every time you access a table with an invalid (old) file name.
• When searching on key values you may not find all rows
• You will get an error "ERROR 1459 (HY000): Table upgrade required" when accessing the table.
• You may get crashes

"mysql_upgrade" works by calling mysqlcheck with different options and running the "mysql_fix_privileges" script. If you have trouble with "mysql_upgrade", you can run these commands separately to get more information of what is going on.

Most of the things in the MySQL 5.1 manual section also applies to MariaDB.

The following differences exists between "mysql_upgrade" in MariaDB and MySQL (as of MariaDB 5.1.50):

• MariaDB will convert long table names properly.
• MariaDB will convert InnoDB tables (no need to do a dump/restore or ALTER TABLE).
• MariaDB will convert old archive tables to the new 5.1 format (note: new feature in testing).
• "mysql_upgrade --verbose" will run "mysqlcheck --verbose" so that you get more information of what is happening.