如何运行 BigQuery 查询，然后将输出 CSV 发送到 Apache Airflow 中的

Question

我需要在 python 中运行一个 bigquery 脚本，它需要在谷歌云存储中输出为 CSV。目前，我的脚本触发大查询代码并直接保存到我的电脑。但是，我需要让它在 Airflow 中运行，所以我不能有任何本地依赖项。我当前的脚本将输出保存到我的本地机器，然后我必须将它移动到 GCS。上网查了一下，搞不明白。（ps我对python很陌生，所以如果之前有人问过这个问题，我提前道歉！）import pandas as pdfrom googleapiclient import discoveryfrom oauth2client.client import GoogleCredentialsdef run_script():    df = pd.read_gbq('SELECT * FROM `table/veiw` LIMIT 15000',                 project_id='PROJECT',                 dialect='standard'                 )    df.to_csv('XXX.csv', index=False)def copy_to_gcs(filename, bucket, destination_filename):    credentials = GoogleCredentials.get_application_default()    service = discovery.build('storage', 'v1', credentials=credentials)    body = {'name': destination_filename}    req = service.objects().insert(bucket=bucket,body=body, media_body=filename)    resp = req.execute()current_date = datetime.date.today()filename = (r"C:\Users\LOCALDRIVE\ETC\ETC\ETC.csv")bucket = 'My GCS BUCKET'str_prefix_datetime = datetime.datetime.now().strftime('%Y%m%d_%H%M%S')destfile = 'XXX' + str_prefix_datetime + '.csv'print('')    ```

Answer 1

Airflow 提供了多个运算符来使用 BigQuery。

• BigQueryOperator在 BigQuery 上执行查询。

• BigQueryToCloudStorageOperator将 BigQuery 表（例如查询的目标表）导出到 GCS。

您可以在 Cloud Composer 代码示例 中查看运行查询的示例，然后将结果导出为 CSV。

# Copyright 2018 Google LLC

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#     https://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# Query recent StackOverflow questions.

bq_recent_questions_query = bigquery_operator.BigQueryOperator(

    task_id='bq_recent_questions_query',

    sql="""

    SELECT owner_display_name, title, view_count

    FROM `bigquery-public-data.stackoverflow.posts_questions`

    WHERE creation_date < CAST('{max_date}' AS TIMESTAMP)

        AND creation_date >= CAST('{min_date}' AS TIMESTAMP)

    ORDER BY view_count DESC

    LIMIT 100

    """.format(max_date=max_query_date, min_date=min_query_date),

    use_legacy_sql=False,

    destination_dataset_table=bq_recent_questions_table_id)

# Export query result to Cloud Storage.

export_questions_to_gcs = bigquery_to_gcs.BigQueryToCloudStorageOperator(

    task_id='export_recent_questions_to_gcs',

    source_project_dataset_table=bq_recent_questions_table_id,

    destination_cloud_storage_uris=[output_file],

    export_format='CSV')