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October 5, 2007

Preparing for the New Daylight Saving Time

Filed under: Uncategorized — heliodias @ 2:02 pm

from Rich Niemiec, TUSC

On August 8, 2005, President George W. Bush signed the Energy Policy Act of 2005. This Act changed the time change dates for Daylight Saving Time in the U.S. Beginning in 2007, DST will begin on the second Sunday in March and end the first Sunday in November. The Secretary of Energy will report the impact of this change to Congress.

This can impact your systems several different ways:

Operating System

UNIX, Linux, and Mac OS use the zoneinfo utility which allows a single time zone to have multiple daylight saving time rules to handle changes from year to year. The zoneinfo database is a collaborative compilation of information about the world’s time zones. New editions of the database are published as changes warrant, with the latest edition being the 2006g edition (2006-05-08) which lists 387 primary time zones and contains the new time changes.  This can be obtained from your O/S vendor.

Oracle Database

This issue will affect Oracle Server – Enterprise Edition – Versions 8.1 to 10.2. Depending on the version of your database, the impact will differ. 

In short, a database patch and a JVM may need to be applied. Once applied, a script provided by Oracle called utltzuv2.sql will need to be run. This will tell you if any code in the db needs to be modified.

Several notes exist on MetaLink regarding this change. Those notes are the following: 

Java

Java uses a similar database to UNIX, so rules for multiple years, and not just the current year can be represented. This database is integrated into the JRE and is separate from the underlying operating system’s time zone database, so the JRE must also be updated when DST rules change. 

The Oracle Java Virtual Machine (JVM) in the database has its own knowledge of time zones, which needs to be updated.  These fixes are included in the following patch sets:

  • 9.2.0.8 
  • 10.1.0.6 
  • 10.2.0.3
  • In Oracle 11 these fixes are part of the base release

Oracle Applications

Oracle says that the E-Business Suite doing the following may be impacted:

  • Database running in an affected time zone 
  • Users with the Client Timezone profile option set to affected time zones
  • Product communications to and from another system running in an affected time zone
  • Product features that have specific time zone functionality

In short, the following patches will need to be applied:

  • FND patch 5619414
  • Forms patch 5445721

Client

Before proceeding with patching the database make sure that you realize the impact this has on the client and middle-tier setup. You will need to patch any ‘client’ that connects to this database and uses the affected time zones as well. This includes “real” clients that connect to the database in client/server mode, but also middle-tiers like Oracle Application Server, which connect to the database. This is further documented in Note ID: 396426.1.

Effects on client and middle-tier of applying time zone patches on the Oracle Database

There is no need to run the utltzuv2.sql script on the clients before applying these files, as this script is only used to check the data in the database. The clients simply need to have the same version of the time zone files as the database they connect to (when data in the affected time frame is used).

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