使用Cloud Functions实现自动调度程序。

以下是实现代码示例：

from google.cloud import bigquery
from google.cloud import scheduler_v1

project_id = "your-project-id"
location = "us-central1"
bigquery_dataset_name = "your-dataset-name"
table_name = "your-table-name"
pubsub_topic_name = "projects/{}/topics/bq-table-load".format(project_id)
cloud_function_name = "your-cloud-function-name"

client = bigquery.Client()
dataset_ref = client.dataset(bigquery_dataset_name, project=project_id)
table_ref = dataset_ref.table(table_name)

# 检查表是否已经创建完毕，如果是，则创建Pub/Sub订阅。
if client.get_table(table_ref).num_rows != 0:
    publisher = scheduler_v1.PublisherClient()
    target = "projects/{}/locations/{}/functions/{}".format(project_id, location, cloud_function_name)
    topic_path = publisher.topic_path(project_id, pubsub_topic_name)
    scheduler = scheduler_v1.CloudSchedulerClient()
    frequency = "0 0 * * *"
    time_zone = "Asia/Shanghai"
    schedule_name = "bq-table-load-schedule"

    # 定义进行调度的消息数据。
    message_data = "Triggered by BigQuery table load."
    message = {"data": message_data.encode("utf-8")}

    # 配置Cloud Functions定期执行计划。
    schedule = {
        "name": schedule_name,
        "description": "Cloud Function to be executed once the BigQuery table is loaded.",
        "schedule": frequency,
        "time_zone": time_zone,
        "pubsub_target": {
            "topic_name": topic_path,
            "data": message,
        },
    }

    # 将计划添加到Cloud Scheduler。
    job_path = scheduler.location_job_path(project_id, location, schedule_name)
    scheduler.create_job(job_path, schedule)

    print("Successfully created Cloud Scheduler job.")
else:
    print("Table is not yet loaded.")