Migration from MyISAM to InnoDB: Difference between revisions

Latest revision as of 15:16, 21 May 2014

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)

run the innodb script as a webpage http://www.YOUR_MOODLE_SITE/admin/tool/innodb/index.php (v2.2.1 You should be logged into your Moodle site as an administrator - there might be timeout issues on large databases) 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)
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

@@ Line 1: / Line 1: @@
-{{stub}}
+{{Admin tools}}
+This page only applies to administrators using Moodle with a MySQL database as it's about migrating the [http://dev.mysql.com/doc/refman/5.1/en/storage-engines.html MySQL storage engine].
-See [http://moodle.org/mod/forum/discuss.php?d=162871 Documentation for migration from MyISAM to InnoDB] for the current discussion which prompted the creation of this page. --[[User:Frank Ralf|Frank Ralf]] 11:41, 24 November 2010 (UTC)
+== 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 ==
@@ Line 8: / Line 13: @@
 * '''set innodb_file_per_table if required'''. [http://dev.mysql.com/doc/refman/5.1/en/innodb-multiple-tablespaces.html 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)==
+== Various Methods described in Moodle forums (choose one)==
-* run the innodb script as a webpage http://www.YOUR_MOODLE_SITE/admin/innodb.php  (there might be timeout issues on large databases and it only works with mysql)
+* run the innodb script as a webpage <nowiki>http://www.YOUR_MOODLE_SITE/admin/tool/innodb/index.php</nowiki> (v2.2.1 You should be logged into your Moodle site as an administrator - there might be timeout issues on large databases) 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, mysql only, and the config.php must only have one moodle instance, but has no timeout issues)
+* 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)
 * 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 [http://moodle.org/mod/forum/discuss.php?d=162002]
-* 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)
+* 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.'''
-* [https://sites.google.com/site/moodlemayhem/tcea2011-moodle-server-setup-basics/moodleacidtrip|Follow the process outlined here]
+* 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==
+* [http://tag1consulting.com/MySQL_Engines_MyISAM_vs_InnoDB MySQL Engines: MyISAM vs. InnoDB] article by Tag1 Consulting
+* [http://code.openark.org/blog/mysql/useful-sed-awk-liners-for-mysql An easy migration of MyISAM mysqldump to InnoDB]
+Using Moodle forum discussions:
+*[http://moodle.org/mod/forum/discuss.php?d=162871 Documentation for migration from MyISAM to InnoDB]
+*[http://moodle.org/mod/forum/discuss.php?d=117913 New moodle.org]
-== Difference between MyISAM and InnoDB ==
+[[fr:Migration de MyISAM vers InnoDB]]
-* read [http://tag1consulting.com/MySQL_Engines_MyISAM_vs_InnoDB]
+[[de:Migration von MyISAM zu InnoDB]]
-* InnoDB is best for data integrity, not so good for searching large files, and uses up more CPU cycles and storage space than MyISAM equivalent
+[[ja:MyISAMからInnoDBへの移行]]
-* InnoDB is much younger than MyISAM but is becoming increasingly attractive ... but because it is more complex, some utilities written for MyISAM like mysqlhotcopy may not work
-* It is perfectly OK to select InnoDB for certain tables, and MyISAM for others (based on above criteria)
-[[fr:admin/innodb]]