Adopting new capabilities in Db2 13 continuous delivery

In Db2 13, function levels and application compatibility levels control the adoption of most new capabilities by Db2 subsystems and Db2 applications.

About this task

Function levels are specified by strings that correspond to the Db2 version, release, and maintenance value. The format is VvvRrMmmm, where vv is the version, r is the release, and mmm is the modification level. For example, V13R1M505 identifies function level 505. For a list of all available function levels in Db2 13, see Db2 13 function levels. Often function level identifiers are abbreviated. For example, function level 505 refers to V13R1M505.

Tip: You can determine the catalog level and function level for a Db2 subsystem or data sharing group, and the code levels of individual subsystems or members, by issuing DISPLAY GROUP commands. For more information, see Determining the Db2 code level, catalog level, and function level

To manage the adoption of new capabilities in Db2 13, use the following overall process:

1. Apply maintenance to bring the Db2 subsystem to the required code level or higher.
   Tip: Apply the maintenance for a code level well before you tailor the catalog level or activate a function level. By doing so, you can verify that Db2 can continue run at the required code level, while you still have the opportunity to identify and remove any problematic maintenance items.

   Important: Do not attempt to start Db2 at any code level that is lower than the highest ever activated function level, even at the lower star (*) function level. Activate a function level only after you are satisfied that Db2 can continue to run at the required code level.
2. If necessary, update the Db2 catalog.
   You can use a single CATMAINT job that specifies the target function level. If the target function level requires multiple catalog level updates, the CATMAINT job processes each update in sequential order. If a later update in the sequence fails, the previous successful updates do not roll back, and the catalog level remains at the highest level reached. If that occurs, you can correct the reason for the failure and resubmit the same CATMAINT job. Some function levels do not require catalog changes.

   Db2 13 function levels use the following Db2 catalog levels:

   • V13R1M505
   • V13R1M504
   • V13R1M501
   • V13R1M100

   Important: Do not attempt to start Db2 at a lower code level after any part of the CATMAINT job for a higher function level completes. Run the CATMAINT job only after you are satisfied that Db2 can continue to run at the necessary code level. The code to tolerate catalog changes is contained in the code level that delivers the CATMAINT job.
3. Activate the higher function level.
   Some new capabilities and enhancements become available immediately. Optimization enhancements become available after the next full prepare of the SQL statements. The application compatibility level of each application continues to control the use of new SQL capabilities.
4. When you are ready for applications, and objects such as routines or triggers, to use new SQL capabilities of the higher function level, rebind or alter them at the higher application compatibility level. Do this only after you are satisfied that Db2 13 is stable at the higher function level.
   You might need to adjust your applications for incompatible changes before they can run at the higher application compatibility level.

   Tip: Do not raise the default application compatibility level of the Db2 subsystem immediately after migrating or activating a new function level. Instead, wait until applications have been verified to work correctly at the higher function level, and any incompatibilities have been resolved. For details, see Enabling default application compatibility with function level 500 or higher.