# ---!Ups
alter table application_users drop column secret_key;
alter table users add column secret_key varchar(36) not null;
drop index application_users_idx;
create index users_secret_key_idx on users (username, secret_key);

# ---!Downs
alter table application_users add column secret_key varchar(36) not null;
alter table users drop column secret_key;
create index application_users_idx on application_users (user_id, secret_key);

Make users have secret keys, not the user/app relationship.
Make users have secret keys, not the user/app relationship.
