使用Airflow提供的迭代器API，显式地使用迭代器来处理结果。

在BigQueryGetDataOperator的execute方法中，使用BigQueryCursorIterator迭代器迭代结果，返回一个迭代器供后续任务使用。以下是代码示例：

from airflow.contrib.hooks.bigquery_hook import BigQueryHook
from airflow.contrib.utils.bigquery_iterator import BigQueryCursorIterator
from airflow.models import BaseOperator
from airflow.utils.decorators import apply_defaults


class BigQueryGetDataOperator(BaseOperator):

    @apply_defaults
    def __init__(
            self,
            sql,
            destination_dataset_table=None,
            bigquery_conn_id='bigquery_default',
            delegate_to=None,
            use_legacy_sql=True,
            *args,
            **kwargs):
        super(BigQueryGetDataOperator, self).__init__(*args, **kwargs)
        self.sql = sql
        self.destination_dataset_table = destination_dataset_table
        self.bigquery_conn_id = bigquery_conn_id
        self.delegate_to = delegate_to
        self.use_legacy_sql = use_legacy_sql

    def execute(self, context):
        hook = BigQueryHook(
            bigquery_conn_id=self.bigquery_conn_id,
            use_legacy_sql=self.use_legacy_sql,
            delegate_to=self.delegate_to
        )
        conn = hook.get_conn()

        cursor = conn.cursor()
        cursor.execute(self.sql)
        iterator = BigQueryCursorIterator(cursor)
        return iterator

在使用此操作符时，接收到迭代器再使用它，例如：

data = BigQueryGetDataOperator(
    task_id='get_data',
    sql='SELECT * FROM my_table'
)

for row in data.execute(None):
    process(row)