https://github.com/apache/airflow/blob/main/airflow/cli/commands/task_command.py#L145
"""For storage of arbitrary notes concerning the dagrun instance."""
    __tablename__ = "dag_run_note"
    user_id = Column(
        Integer,
        ForeignKey("ab_user.id", name="dag_run_note_user_fkey"),
        nullable=True,
    )
    dag_run_id = Column(Integer, primary_key=True, nullable=False)
    content = Column(String(1000).with_variant(Text(1000), "mysql"))
    created_at = Column(UtcDateTime, default=timezone.utcnow, nullable=False)
    updated_at = Column(UtcDateTime, default=timezone.utcnow, onupdate=timezone.utcnow, nullable=False)
    dag_run = relationship("DagRun", back_populates="dag_run_note")
    __table_args__ = (
        PrimaryKeyConstraint("dag_run_id", name="dag_run_note_pkey"),
        ForeignKeyConstraint(
            (dag_run_id,),
            ["dag_run.id"],
            name="dag_run_note_dr_fkey",
            ondelete="CASCADE",
        ),
    )
    def __init__(self, content, user_id=None):
        self.content = content
        self.user_id = user_id
    def __repr__(self):
        prefix = f"<{self.__class__.__name__}: {self.dag_id}.{self.dagrun_id} {self.run_id}"
        if self.map_index != -1:
            prefix += f" map_index={self.map_index}"
        return prefix + ">"