Daylight Saving Time 2007—Databases: MySQL

MySQL Overview

MySQL is an open-source relational database management system (RDBMS) that powers millions of websites worldwide. While lacking the maturity and data robustness of larger databases such as Oracle and PostgreSQL, MySQL is very fast and lightweight making it ideal for applications that are not mission-critical or where powerful hardware is not available.

Impact of Daylight Saving Time Change on this Technology

MySQL is capable of performing date/time calculations internally. It is important that MySQL recognize the DST change for applications that are using MySQL to handle their date/time needs. ITS maintains a small handful of MySQL databases for internal use so there should be no customer impact.

Remediation Steps for Customers

If you are maintaining a MySQL server, the remediation process depends on the version of MySQL that you are running. Regardless of version, make sure that your operating system is aware of the DST change.

Versions of MySQL older than 4.1.3 without time zone support always use the operating system time. If the operating system is aware of the DST change then MySQL should also be aware.

MySQL 4.1.3 and newer includes its own time zone tables, and remediation depends on whether the host operating system contains its own zoneinfo database.

If the operating system does not have a zoneinfo database (i.e. Windows, HP-UX):

1. Download the latest time zone table file at http://dev.mysql.com/downloads/timezones.html
2. Shutdown your MySQL server
3. Extract the .frm, .MYI, and .MYD files to the mysql/ subdirectory of your server’s MySQL data directory.
4. Start your MySQL server back up

If the operating system has its own zoneinfo database (i.e. FreeBSD, Linux, Solaris):

1. Make sure that your system is compatible with the DST changes.
2. Use the mysql_tzinfo_to_sql script to update MySQL’s time zone tables using data from the system’s zoneinfo database:
   
   shell> mysql_tzinfo_to_sql /path/to/zoneinfo | mysql -u root mysql

Additional Information

http://dev.mysql.com/doc/refman/4.1/en/time-zone-support.html

MySQL 5.0 Information:
http://dev.mysql.com/doc/refman/5.0/en/time-zone-support.html

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