Known Issues for MySQL

Configuring Database Character Encoding

To prevent problems with character encoding, for consistency, we recommend to use Unicode character encoding UTF-8 among all the entities of your system. See Configuring Database Character Encoding for more details.

MySQL Storage Engine

The Default storage engine for MySQL is MyISAM. This storage engine does not support Foreign Key constraints. This may cause data corruption and is not recommended for use.

You can set the default Storage Engine for MySQL by passing the '--default-storage-engine=InnoDB' option when starting mysql.

For more information see: http://dev.mysql.com/doc/refman/4.1/en/storage-engines.html.

MySQL JDBC Drivers

For users using MySQL with Confluence 2.2 (or higher), please ensure that you are using the latest (3.1.14) MySQL Java Connector. Earlier versions of the MySQL connector have a bug which is triggered by improvements in Confluence 2.2. These earlier connector versions will result in an error being recorded in your logs on upgrade (and will result in unstable operation of Confluence)

ERROR [hibernate.tool.hbm2ddl.SchemaUpdate] execute could not complete schema update

You can download the latest MySQL connector from the MySQL Java Connector 3.1 download page. Please be sure that you remove any older versions of the connector from your application server.

Don't use the debug version of these drivers (the jar file ending in '-g.jar'). This requires extra configuration, see Installing the Driver and Configuring the CLASSPATH

If you get a connection error: Access denied for user 'confluenceuser'@'localhost.localdomain' this may be because 127.0.0.1 resolves to 'localhost.localdomain' in your environment. Create a user 'confluenceuser@localhost%' to match any domain starting with localhost.

MySQL and Character encoding:

When specifying a character encoding as part of your mysql connection url (eg: &characterEncoding=utf8), it is important to ensure that the specified encoding is compatible with the default encoding used by your database. Note: if you do not specify a characterEncoding on the connection url, the connection will default to the servers default character set.

Full details of MySQLs character support is available here: http://dev.mysql.com/doc/mysql/en/charset.html

MySQL Dialect class change (if upgrading from Confluence version 2.2 or older) 

If you are using MySQL, and are upgrading Confluence from version 2.2 or older, the 'hibernate.dialect' property in the confluence.cfg.xml file needs to be changed to 'com.atlassian.hibernate.dialect.MySQLDialect' like so:

<property name="hibernate.dialect">com.atlassian.hibernate.dialect.MySQLDialect</property>

Confluence installation Hangs

If the confluence installation hangs after creating the mysql jdbc connection, try setting the jdbc property useServerPrepStmts to false.

Example:

jdbc:mysql://localhost/confluence?autoReconnect=true&useServerPrepStmts=false

This issue is known to happen on Ubuntu and Mysql 4.1.x.

MySQL Connector-J 3.1.10 bug.

If you are wondering why a large number of '!' marks are appearing in your log files, it is likely to be caused by http://bugs.mysql.com/bug.php?id=11629.

BadSqlGrammarException and character encoding exceptions using MySQL Connector-J 3.1.10

User reports that adding a "useOldUTF8Behavior=true" parameter to the JDBC URL allowed Confluence to work with this driver.

DataIntegrityViolationException when running MySQL 5

Running MySQL 5 as the database for Confluence is currently not a supported configuration. However, if it is used, the following exception may occur in the logs:

org.springframework.dao.DataIntegrityViolationException: (Hibernate operation): data integrity violated by SQL ''; nested exception is
java.sql.BatchUpdateException: Data too long for column 'boolean_val' at row 1

A temporary fix for this is to manually modify the boolean_val column in the OS_PROPERTYENTRY table, so that it is of type bit(8). Note that this won't allow you to restore a backup, as the first thing the restore does is rebuild the DB.

java.sql.SQLException: Invalid authorization specification

Some users reported problems getting MySQL running under Tomcat, throwing an exception similar to the following:

Connection failed to open on the JDBC URL: java.sql.SQLException: Invalid authorization specification, message from server: "Access denied for user: 'your_username@localhost.localdomain' (Using password: YES)"

However, it is still possible to easily connect to MySQL from the shell and from PhpMyAdmin.

The problem seems to be a known bug and seems to be related to the hostname portion in mysql:users.

I figured out the problem. Changing "host" in mysql:users to "127.0.0.1" enabled Confluence to access the database.

Therefore instead of granting permissions using the following command:

GRANT ALL PRIVILEGES ON .\* to 'example'@'localhost.localdomain' identified by '<the password>';
 FLUSH PRIVILEGES;

you should use:

GRANT ALL PRIVILEGES ON .\* to 'example'@'127.0.0.1' identified by '<the password>';
 FLUSH PRIVILEGES;

You can do it this way, but it seems you should ensure that the canonical host name is the first item in the /etc/hosts line for 127.0.0.1. Make sure it's not localhost.localdomain but localhost. e.g.:

127.0.0.1     localhost localhost.localdomain myfunkyboxname anotheralias.foobar.com

And then make sure you use the same thing, i.e. localhost in the GRANT line and the JDBC URL. Inconsistency across these things is the root problem (and perhaps we can blame the JDBC Driver?)

Max Allowed Packet Size Exceeded

If you are using MySQL 4 and prior, you may come across a problem with max_allowed_packet size.

ERROR [sf.hibernate.util.JDBCExceptionReporter] logExceptions Packet for query is too large (1259485 > 1048576). You can change this value on the server by setting the max_allowed_packet' variable.

To resolve this problem, you need to increase the value for max_allowed_packet

Prior MySQL 4.0, use this syntax instead:

shell> mysqld --set-variable=max_allowed_packet=16M

From MySQL 4.0, use this syntax

shell> mysql --max_allowed_packet=32M

For more information, please refer to MySQL manual:
http://mysql.bigbiz.com/doc/refman/4.1/en/packet-too-large.html

Duplicate Key Exception During Import

When upgrading to MySQL from another database, such as HSQL, importing the site backup often fails with an error like this:

Duplicate key or integrity constraint violation message from server:

Such errors occur because usually MySQL evaluates unique key constraints and primary key constraints in a case insensitive way. So if you have a space with the key "sp" and another with the key "SP", MySQL will refuse to add the second one.

This problem is avoidable by setting the collation on the database to be case sensitive.

Setting the MySQL Collation to be case sensitive

MySQL uses collations for sorting data and for evaluating uniqueness.

To set the collation to case sensitive when using utf8, use this command:

CREATE DATABASE confluence CHARACTER SET utf8 COLLATE utf8_bin;

Note: The collation must be compatible with the character set.  The name of the database in the example is confluence.

To alter the collation on an existing database using utf8, use this command:

ALTER DATABASE confluence CHARACTER SET utf8 COLLATE utf8_bin;

Note: The collation must be compatible with the character set.  The name of the database in the example is confluence.

For further information see the MySQL documentation on character sets on collations.

Database Timeout Issues when creating a Manual Backup

A problem that some customers have encountered is their Database connection timing out whilst in the middle of performing a Manual Site Backup in Confluence.

This issue is indicated in the log files with the following Error Message:

com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: 

According to the MySQL manual:

The number of seconds the server waits for activity on a non-interactive connection before closing it. This timeout applies only to TCP/IP and Unix socket file connections, not to connections made via named pipes, or shared memory.

On thread startup, the session wait_timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect()). See also interactive_timeout.

This problem is resolved by adjusting the wait_timeout parameter to a higher value.

If problems persist after making the changes, please create a new Support Ticket and our Support Team will assist you.