explain how to add unique options to counter_cache and others...
explain how to add unique options to counter_cache and others...

samchen2009/impressionist,charlotte-ruby/impressionist,charlotte-ruby/impressionist,guodongme/impressionist,samchen2009/impressionist,firmanm/impressionist,samchen2009/impressionist,guodongme/impressionist,charlotte-ruby/impressionist,guodongme/impressionist,firmanm/impressionist,firmanm/impressionist