def fetch_value
	sql = ActiveRecord::Base.connection();
	sql.execute "SET autocommit=0";
	sql.begin_db_transaction
	id, value =
	sql.execute("SELECT id, value FROM sometable WHERE used=0 LIMIT 1 FOR UPDATE").fetch_row;
	sql.update "UPDATE sometable SET used=1 WHERE id=#{id}";
	sql.commit_db_transaction
 
	value;
end