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5.10.8. MySQL Server Time Zone Support

The MySQL server maintains several time zone settings:

  • The system time zone. When the server starts, it attempts to determine the time zone of the host machine and uses it to set the system_time_zone system variable. The value does not change thereafter.

  • The server's current time zone. The global time_zone system variable indicates the time zone the server currently is operating in. The initial value for time_zone is 'SYSTEM', which indicates that the server time zone is the same as the system time zone. The initial value can be specified explicitly with the --default-time-zone=timezone option. If you have the SUPER privilege, you can set the global value at runtime with this statement:

    mysql> SET GLOBAL time_zone = timezone;
    
  • Per-connection time zones. Each client that connects has its own time zone setting, given by the session time_zone variable. Initially, the session variable takes its value from the global time_zone variable, but the client can change its own time zone with this statement:

    mysql> SET time_zone = timezone;
    

The current values of the global and client-specific time zones can be retrieved like this:

mysql> SELECT @@global.time_zone, @@session.time_zone;

timezone values can be given as strings indicating an offset from UTC, such as '+10:00' or '-6:00'. If the time zone information tables in the mysql database have been created and populated, you can also used named time zones, such as 'Europe/Helsinki', 'US/Eastern', or 'MET'. The value 'SYSTEM' can be used to indicate that the time zone should be the same as the system time zone. Time zone names are not case sensitive.

The MySQL installation procedure creates the time zone tables in the mysql database, but does not load them. You must do so manually. (If you are upgrading to MySQL 4.1.3 or later from an earlier version, you should create the tables by upgrading your mysql database. Use the instructions in Section 5.5.2, “mysql_upgrade — Check Tables for MySQL Upgrade”.)

If your system has its own zoneinfo database (the set of files describing time zones), you should use the mysql_tzinfo_to_sql program for filling the time zone tables. Examples of such systems are Linux, FreeBSD, Sun Solaris, and Mac OS X. One likely location for these files is the /usr/share/zoneinfo directory. If your system does not have a zoneinfo database, you can use the downloadable package described later in this section.

The mysql_tzinfo_to_sql program is used to load the time zone tables. On the command line, pass the zoneinfo directory pathname to mysql_tzinfo_to_sql and send the output into the mysql program. For example:

shell> mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

mysql_tzinfo_to_sql reads your system's time zone files and generates SQL statements from them. mysql processes those statements to load the time zone tables.

mysql_tzinfo_to_sql also can be used to load a single time zone file, and to generate leap second information:

  • To load a single time zone file tz_file that corresponds to a time zone name tz_name, invoke mysql_tzinfo_to_sql like this:

    shell> mysql_tzinfo_to_sql tz_file tz_name | mysql -u root mysql
    
  • If your time zone needs to account for leap seconds, initialize the leap second information like this, where tz_file is the name of your time zone file:

    shell> mysql_tzinfo_to_sql --leap tz_file | mysql -u root mysql
    

If your system doesn't have a zoneinfo database (for example, Windows or HP-UX), you can use the package of pre-built time zone tables that is available for download at http://dev.mysql.com/downloads/timezones.html. This package contains .frm, .MYD, and .MYI files for the MyISAM time zone tables. These tables should be part of the mysql database, so you should place the files in the mysql subdirectory of your MySQL server's data directory. The server should be stopped while you do this.

Warning: Please don't use the downloadable package if your system has a zoneinfo database. Use the mysql_tzinfo_to_sql utility instead. Otherwise, you may cause a difference in datetime handling between MySQL and other applications on your system.

For information about time zone settings in replication setup, please see Section 6.8, “Replication Features and Known Problems”.


 
 
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