model 中新增了一个对象 Message 和 并在另一个model中增加外键字段message，然后push到heroku上，同步migrate之后，发现新的表不能用. 但是本地是执行 python manage.py flush 之后同步的，没出问题， 但是在heroku上执行 flush 出错

 CommandError: Database d4e4561s5hscht couldn't be flushed. Possible reasons:
  * The database isn't running or isn't configured correctly.
  * At least one of the expected database tables doesn't exist.
  * The SQL was invalid.
Hint: Look at the output of 'django-admin sqlflush'. That's the SQL this command wasn't able to run.
The full error: cannot truncate a table referenced in a foreign key constraint
DETAIL:  Table "blog_post" references "auth_user".
HINT:  Truncate table "blog_post" at the same time, or use TRUNCATE ... CASCADE.

请问怎么清理数据库