class Person(Base):
    __tablename__ = 'people'
id = Column(Integer, primary_key=True)
discriminator = Column('type', String(50))
__mapper_args__ = {'polymorphic_on': discriminator}


class Engineer(Person):
    __mapper_args__ = {'polymorphic_identity': 'engineer'}
SQLAlchemy - Define a model subclass as a subset of the table