In Postgres, unique constraints are implemented by unique indices (same is true of primary keys). So, you can drop the index that was built for it - check your database directory for file names like "table_name_pkey" for the primary key index. I forget what name is given unique indices but it should be obvious from the ls.
Then go into psql and drop the index, then make your new one.
You can add the column with "alter table add column domain varchar(100)"
I strongly recommend trying this on a test database first, though.
Why the "warning"? This is for your private work, right? I'm not going to wake up to a broken ACS or anything like that, I hope! Only aD themselves get to do that to me! :)
