Object, table and column renamings are supported! These features require database re-creation. You can re-create your database by the following command:
% groonga YOUR_DB dump > db.dump
% groonga -n YOUR_NEW_DB < db.dump
Note
Groonga 1.2.8 can open databases created by groonga 1.2.7 or earlier. But groonga 1.2.7 or earlier can't open databases created by groonga 1.2.8 or later.