I've noticed that after an execution of an ALTER DATABASE SCHEMA FROM FILE command, the .udb size increases, even if no DML execution is done between the database's schema upgrades.
So I had known about this issue, I've executed a set of alter-database-schema commands many times, like this:
Version 0 -> upgrade schema -> Version 1 -> upgrade schema -> Version 2 -> upgrade schema -> Version 0
After the execution of 20 steps (no DML was done), the database size hasn't stabilized as I expected.
Why the database continues grows, even if no data was modified or inserted?