> you can use find_or_create_by to avoid creating duplicate records... 

Thanks.  As you may be able to tell, I'm new to Ruby and RoR.

> however that won't delete records from the db if they are deleted in the tsv.

That's okay.  If we need to, we can do it with "delete * from level_source hint where id != null" or the Ruby equivalent.  Do you think I should put that at the start of the rake task instead of using find_or_create_by?