python-3.x - 将 BigQuery 表导出到 Google Storage 时如何避免标题

Question

我开发了下面的代码，它有助于将 BigQuery 表导出到 Google 存储桶中。我想将文件合并到没有标题的单个文件中，以便下一个进程将使用文件而没有任何问题。

    def export_bq_table_to_gcs(self, table_name):
        client = bigquery.Client(project=project_name)

        print("Exporting table {}".format(table_name))
        dataset_ref = client.dataset(dataset_name,
                                     project=project_name)
        dataset = bigquery.Dataset(dataset_ref)
        table_ref = dataset.table(table_name)
        size_bytes = client.get_table(table_ref).num_bytes

        # For tables bigger than 1GB uses Google auto split, otherwise export is forced in a single file.
        if size_bytes > 10 ** 9:
            destination_uris = [
                      'gs://{}/{}{}*.csv'.format(bucket_name,
                                       f'{table_name}_temp', uid)]
        else:
            destination_uris = [
                      'gs://{}/{}{}.csv'.format(bucket_name,
                                      f'{table_name}_temp', uid)]

        extract_job = client.extract_table(table_ref, destination_uris)  # API request
        result = extract_job.result()  # Waits for job to complete.

        if result.state != 'DONE' or result.errors:
            raise Exception('Failed extract job {} for table {}'.format(result.job_id, table_name))
        else:
            print('BQ table(s) export completed successfully')
        storage_client = storage.Client(project=gs_project_name)
        bucket = storage_client.get_bucket(gs_bucket_name)
        blob_list = bucket.list_blobs(prefix=f'{table_name}_temp')
        print('Merging shard files into single file')
        bucket.blob(f'{table_name}.csv').compose(blob_list)

你能帮我找到一种跳过标题的方法吗？

谢谢，

拉古纳特。

标签： python-3.xgoogle-bigquerygoogle-cloud-storage

Answer 1

我们可以通过使用 jobConfig 将 print_header 参数设置为 False 来避免 header。示例代码

job_config = bigquery.job.ExtractJobConfig(print_header=False)
extract_job = client.extract_table(table_ref, destination_uris,
                                   job_config=job_config)

谢谢