Why do some Microsoft Hotfixes cause issues with UNIFI? - WKB12928

ENVIRONMENT

• UNIFI  1.5/1.5.1
• UNIFI 1.6/1.6.1
• UNIFI 1.7 /1.7.1
• UNIFI 1.8/1.8.1 

ANSWER

Here is the higher-level information related to the architectural issues that cause incompatibilities with certain Windows Time Zone updates.

UNIFI and Time Zone Handling

UNIFI, by design, always stores and displays time stamps in the user’s local time zone. The data type used for storing this information is the Oracle data type “TIMESTAMP(7) WITH TIME ZONE”. However, when displaying these values to the user, they are converted from Oracle time zones to Windows time zones. This conversion also happens when the data is stored in the database. It starts on a client machine with a Windows time zone and it is converted to the Oracle time zone before it is stored in the database. 

The conversion between Windows and Oracle time zones is necessary because the two systems use different time zone lists and descriptions. UNIFI performs the conversion based on a “catalog” that maps Windows time zones to Oracle time zones. This catalog is maintained by UNIFI, and it must be updated every time Oracle or Windows updates its own list of time zones. Failing to update the catalog results in UNIFI errors and, eventually, inconsistencies in the data. 

Microsoft can release time zone updates at any time as these changes occur throughout the world. Previously, Microsoft released these as individual Windows Updates that could be omitted or removed from a system to resolve the problem. Microsoft's new strategy is to bundle these types of updates with others critical patches in monthly roll-ups, which now make this issue more of a concern.

This issue has been identified with multiple Windows Updates in versions of UNIFI prior to 1.8.2, and it requires a patch to update the catalog. UNIFI 1.8.2 has been updated to reflect the latest changes in time zones; however, a new update may impact UNIFI 1.8.2 as well. This issue is tracked under defect number US1#206946. 

Waters has identified this as an architectural design that could be improved, and it plans to address it, with high priority, in a future version.
 

ADDITIONAL INFORMATION