Migration from MyISAM to InnoDB

This page only applies to administrators using Moodle with a MySQL database as it's about migrating the MySQL storage engine.

Why migrate to InnoDB?

InnoDB is highly recommended rather than MyISAM because it works more robustly, performs better with big sites and allows better data integrity features (transactions).

It is required if you want to use Moodle's Web services (for the Mobile app for example), and possibly for more features in future.

MySQL Configuration

Before attempting to change the table type, you should:

• check InnoDB is enabled. Log in to MySQL and run the command SHOW ENGINES. Make sure that support for InnoDB shows either "YES" or "DEFAULT".
• set innodb_file_per_table if required. This setting can be useful for large installations, but it only affects newly created tables and can't be applied retrospectively.

Various Methods described in Moodle forums (choose one)

• Make sure nobody else is accessing the server while performing the following. Put Moodle into maintenance mode. As an administrator, run the innodb script as a webpage http://www.YOUR_MOODLE_SITE/admin/tool/innodb/index.php. (With large databases, you may experience time-out issues.) Add the following statement to /etc/my.cnf under the [mysqld] heading: "binlog_format=ROW" (without the quotes) and stop/restart MySQL. Without this statement you will encounter the dmlwriteexception error when moodle attempts to write to MySQL.
• use the CLI script in admin/cli/mysql_engine.php - requires access to shell, and the config.php must only have one moodle instance, but has no timeout issues, it is recommended to use CLI maintenance mode during the conversion
• use PHPMyAdmin entering Structure view of a table and clicking Operations tab. Look for Storage Engine parameter. This is a tedious task due to the number of tables [1]
• perform a database dump (e.g. mysqldump moodle_database > dump.SQL), use an editor or sed/perl/awk command to find/replace , replacing MyISAM with InnoDB. Finally, restore back in the server. (e.g. mysql < dump.SQL or equivalent). If using this method, be very careful to use the same file encoding on both input and output.
• Follow the process detailed here - https://sites.google.com/site/moodlemayhem/tcea2011-moodle-server-setup-basics/moodleacidtrip
• Use the php script (Tested on 1.9 and 2.0/2.2) http://noveckg.blogspot.com/2012/04/moodle-php-script-to-convert-mysql.html

See also

• MySQL Engines: MyISAM vs. InnoDB article by Tag1 Consulting
• An easy migration of MyISAM mysqldump to InnoDB

Using Moodle forum discussions:

• Documentation for migration from MyISAM to InnoDB
• New moodle.org