"""Base class for XCom objects."""
    __tablename__ = "xcom"
    dag_run_id = Column(Integer(), nullable=False, primary_key=True)
    task_id = Column(String(ID_LEN, **COLLATION_ARGS), nullable=False, primary_key=True)
    map_index = Column(Integer, primary_key=True, nullable=False, server_default=text("-1"))
    key = Column(String(512, **COLLATION_ARGS), nullable=False, primary_key=True)
    
    dag_id = Column(String(ID_LEN, **COLLATION_ARGS), nullable=False)
    run_id = Column(String(ID_LEN, **COLLATION_ARGS), nullable=False)
    value = Column(LargeBinary)
    timestamp = Column(UtcDateTime, default=timezone.utcnow, nullable=False)
    __table_args__ = (
        
        
        
        Index("idx_xcom_key", key),
        Index("idx_xcom_task_instance", dag_id, task_id, run_id, map_index),
        PrimaryKeyConstraint(
            "dag_run_id", "task_id", "map_index", "key", name="xcom_pkey", mssql_clustered=True
        ),
        ForeignKeyConstraint(
            [dag_id, task_id, run_id, map_index],
            [
                "task_instance.dag_id",