Implications of falling back

Before you fall back to your previous Db2 version, consider the implications of doing so.

Data sharing

If any member of a data sharing group needs to fall back, consider the implications for data sharing. For more information about falling back in a data sharing environment, see Falling back in a data sharing environment.

Frozen objects

Falling back does not undo changes that the migration process made to the catalog. Db2 uses the migrated catalog after fallback. Some objects in this catalog that have been affected by Db2 12 function might become frozen objects after fallback. Frozen objects are unavailable, and they are marked with the release dependency marker Q. If an object is marked with a release dependency, it remains marked forever. The release dependency marker is listed in the IBMREQD column of catalog tables. The following table lists the objects that are frozen when you fall back to a previous release.

Table 1. Objects that are frozen after fallback
RELEASE DEPENDENT MARK = Q
Plans, packages, or views that use any new syntax, objects, or bind options DBRMs that are produced by a precompile in Db2 12 with a value of V12 for the NEWFUN option and when any new Db2 12 functions are being used

Plans and packages become frozen objects when they use new SQL syntax, use new BIND options and attributes, or reference frozen objects. When plans and packages become frozen objects, the automatic rebind process is adversely affected.

Begin general-use programming interface information.

After falling back, you can determine if any of your objects are frozen by issuing the following statement:

SELECT * FROM catalog table
WHERE IBMREQD = 'Q'

End general-use programming interface information.

Automatic rebind

After fallback, if you specified YES or COEXIST for the ABIND subsystem parameter, plans or packages that are bound in Db2 12 are automatically rebound on their first execution in Db2 11. If you specified NO for the ABIND subsystem parameter, this automatic rebind fails.

The automatic rebind also fails if you try to use plans or packages that are frozen. To make available the plans and packages that were not automatically rebound on Db2 11, change the SQL statements or remove the reference to a frozen object, precompile the application programs, and explicitly bind the plans and packages on Db2 11.

Administrative task scheduler tasks

After fallback, all tasks that are managed by the administrative task scheduler in Db2 Db2 12 are not manageable by the administrative task scheduler in Db2 Db2 11 because of the higher task version. Use ADMIN_TASK_ADD in Db2 11 to delete and reinsert all tasks. You can use the ADMIN_TASK_LIST table user-defined function to read and store the characteristics of the tasks in a user table before you fall back.