During using odoo10, I find the model's id_seq is GONE:

the first time install the model, it is all well running, but after a few days after(with a corn job), the server is throw out the error:

    ProgrammingError: relation "product_ho_price_report_id_seq" does not exist

I'm sure this id_seq is created by the server the first time when install, but why the id_seq just disappeared?