Compatibility Considerations

MyISAM storage engine

MyISAM (the default storage engine for MySQL) does not support transactions. If there is an error while data is being saved to the database, XWiki will attempt to rollback the transaction to it's previous known good state. If you use MyISAM it will do nothing, leaving the database in whatever state it was in when the error occurred.
If you use MySQL with default engine MyISAM, you will most likely corrupt your database. We highly recommend using a storage engine such as InnoDB which supports transactions.

MySQL versions older than 5.0

XWiki does not fully work with MySQL versions 4.x or lower, due to several limitations of the way the SQL standards are implemented in MySQL, limited support for non-latin1 encodings, the flaky integration of Hibernate and MySQL 4, and other things. Most of the application works fine, but there are some parts that cannot easily be fixed, so if you must use MySQL 4.x, you're doing it on your own. Seriously, MySQL 4 is pretty old and buggy, you should consider upgrading.

Installation Steps

Follow these instructions:

• Download and install MySQL 5.X or greater.
• Start the MySQL server. You can do that in several ways. For example:
  mysqld --console
• Create the wiki database. You can do that in several ways. For example:
  mysql -u root -e "create database xwiki default character set utf8"
• Give all privileges to the xwiki user for accessing the xwiki database. You can do that in several ways. For example (if you get connections problems try localhost instead of the IP address below):
  mysql -u root -e "grant all privileges on xwiki.* to xwiki@localhost identified by 'xwiki'"
• Please make sure that the DNS-name "localhost" is defined in your hosts-file (i.e. /etc/hosts)
• You need to have the MySQL JDBC Driver JAR (named mysql-connector-java*.jar installed in XWiki's WAR file. If this file isn't present in XWiki's WEB-INF/lib directory you'll need to download it and copy it there. You can download it from the MySQL Connector/J Driver page or directly from the Maven Central Repository.
• Now you need to tell XWiki to use MySQL. To do this, edit the WEB-INF/hibernate.cfg.xml file where you have expanded the XWiki WAR file and replace the matching properties with the following ones:
  <property name="connection.url">jdbc:mysql://localhost/xwiki</property>
  <property name="connection.username">xwiki</property>
  <property name="connection.password">xwiki</property>
  <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
  <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

Troubleshooting

Can't create test file

When running mysqld --console you may get the following (especially if you're on Mac):

To start MySQL run the following instead:

Data Truncation Error

If you receive an Exception like the following while installing/upgrading XWiki, chances are, that you are using an outdated version of MySQLConnectorJ.

On Linux, mysql-connector-java-3.x has proven not to work due to a bug in the handling of UTF-8, and lack of support for Boolean types.

Upgrading to the latest version of MySQLConnectorJ should solve such an error in most of the cases.