Is there a way to find the difference between db indexes between versions?
For instance, is there a list of index changes between v12 and 21? NK_AH_IDNR_bearb was mentioned in the documentation, but are there others that were as well?
The best way to check this is to compare the uc_ddl.sql files between versions (using something like a diff or the notepad++ compare plugin). For example, if upgrading from 12.3 to 21.0 on oracle, look at the following articles (relative to the /db directory):
db\oracle\12.3\uc_ddl.sql
db\oracle\21.0\uc_ddl.sql