Google bigquery导出表到Google Cloud存储中的多个文件，有时一个文件 [英] Google bigquery export table to multiple files in Google Cloud storage and sometimes one single file

问题描述

我正在使用Bigquery python库将csv格式的Bigquery表中的数据导出到GCS中.

I am using Bigquery python libraries to export data from Bigquery tables into GCS in csv format.

我给出了一个通配符模式，假设某些表可以超过1 GB

I have given a wildcard pattern assuming some tables can be more than 1 GB

有时，即使表只有几MB，它也会创建多个文件，有时只是创建一个文件.

Sometimes even though table is few MB it creates multiple files and sometimes just it creates just 1 file.

这背后有逻辑吗?

我的导出工作流程如下:

My export workflow is the following:

project = bq_project dataset_id = bq_dataset_id table_id = bq_table_id     
bucket_name =bq_bucket_name workflow_name=workflow_nm 
csv_file_nm=workflow_nm+"/"+csv_file_prefix_in_gcs+'*'client = 
bigquery.Client() destination_uri = "gs://{}/{}".format(bucket_name, 
csv_file_nm) dataset_ref = client.dataset(dataset_id, project=project) 
table_ref = dataset_ref.table(table_id) destination_table = 
client.get_table(dataset_ref.table(table_id)) configuration = 
bigquery.job.ExtractJobConfig() configuration.destination_format='CSV' – 
csv_file_nm=workflow_nm+"/"+csv_file_prefix_in_gcs 

推荐答案

我认为这是导出的预期行为. Bigquery Export 文档指定以下内容:

I think this is an intended behaviour of the export. The Bigquery Export documentation specifies the following:

将数据导出到多个文件时，文件大小将变化.

When you export data to multiple files, the size of the files will vary.

这与您在导出中看到的行为相对应.

This corresponds to the behavior you are seeing in your exports.

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