GEN: Daylight Savings Time impact on Red Gate Products

Brian Donahue

• Date: 5 February 2007
• Products Affected: All

The change to Daylight Savings Time in the United States is moving forward, effective this year, under the U.S. Energy Policy Act 2005. This will affect automated computer systems that have a built-in algorithm for setting the system clocks forwards and backwards on the appropriate days, because these algorithms need to be modified in order to set the real-time clock of a computer system at the new time. This work is normally carried out by a computer’s operating system (for instance, any version of Microsoft Windows), but other pieces of software may contain their own individual calendaring functions and could be affected by the change in Daylight Savings Time.

None of the software currently produced by Red Gate Software Limited contains any time algorithms that would be affected by a change in the day that the clock is set backwards or forwards, so there should be no direct effects on any Red Gate products. There are a few potential issues to note, however, in the interest of maintaining the proper operation of your software:

• SQL Backup scheduled backups, which are run by Microsoft SQL Server Agent, may be affected if the appropriate updates recommended by Microsoft are not followed.
• SQLCOMPARE.exe and SQLDATACOMPARE.exe, the command-line variants of SQL Compare and Data Compare, may be using Windows Scheduled Tasks. Again, please ensure Microsoft’s recommended updates for Microsoft Windows are applied to prevent problems with any scheduled tasks.
• Running any programs during the time change (such as ANTS Profiler) could be affected, but this is no different than if there was no change to Daylight Savings Time.
• The change in time should not affect the two-week free evaluation period of Red Gate’s products. Rewinding the system clock could potentially invalidate any running trials of Red Gate’s products, but this anti-tamper feature has been given a safety margin of more than an hour.

For more information about this issue, please reference:

US Energy Policy Act 2005 (http://frwebgate.access.gpo.gov/cgi-bin ... ubl058.109)

Preparing for Daylight Savings Time 2007 (Microsoft) (http://www.microsoft.com/windows/timezone/dst2007.mspx)