我有大约30个表与深层多级关联.是否有一种“简单”的方法将所有当前ID转换为UUID？

从这个：https://coderwall.com/p/n_0awq,我可以看到我可以在迁移中改变表格.我在想这样的事情：

for client in Client.all
  # Retrieve children
  underwritings = client.underwritings
  # Change primary key
  execute 'ALTER TABLE clients ALTER COLUMN id TYPE uuid;'
  execute 'ALTER TABLE clients ALTER COLUMN id SET DEFAULT uuid_generate_v1();'
  # Get new id - is this already generated?
  client_id = client.id
  for underwriting in underwritings
    locations = underwriting.locations
    other_record = underwriting.other_records...

    execute 'ALTER TABLE underwritings ALTER COLUMN id TYPE uuid;'
    execute 'ALTER TABLE underwritings ALTER COLUMN id SET DEFAULT uuid_generate_v1();'
    underwriting.client_id = client_id
    underwriting.saved
    underwriting_id = underwriting.id

    for location in locations
      buildings = location.buildings
      execute 'ALTER TABLE locations ALTER COLUMN id TYPE uuid;'
      execute 'ALTER TABLE locations ALTER COLUMN id SET DEFAULT uuid_generate_v1();'
      location.undewriting_id = underwriting_id
      location.save
      location_id = location.id

      for building in buildings
      ...
      end
    end
    for other_record in other_records
      ...
    end
    ... 
    ...
  end
end

问题：

>这会有用吗？
>有更简单的方法吗？
>只要在更改主键之前检索子记录,是否可以正确检索子记录？
>一旦调用alter table,是否已经生成了新的主键？

非常感谢您提供帮助或提示.