How to check when BigQuery query result returns zero records?

Question

I have a client API in python which executes BigQuery job to trigger a query and write query result into respective BigQuery table. How to determine whether that query result returns zero records at any execution or not?

Python code:

def main(request):

    query = "select * from `myproject.mydataset.mytable`"
    client = bigquery.Client()
    job_config = bigquery.QueryJobConfig()
    dest_dataset = client.dataset(destination_dataset, destination_project)
    dest_table = dest_dataset.table(destination_table)
    job_config.destination = dest_table
    job_config.create_disposition = 'CREATE_IF_NEEDED'
    job_config.write_disposition = 'WRITE_APPEND'
    job = client.query(query, location='US', job_config=job_config)
    job.result()

I want If query result is having none record then it should print some message for me. Can anybody suggest how to get this done.

user_291180 · Answer

QueryJob.result() returns a RowIterator, which has a property called total_rows.

So, something like:

result = job.result()
if result.total_rows == 0:
  print('no results')

Documentation: RowIterator.total_rows

Updated per @Dom Zippilli's comment: . total_rows is what you're looking for.

How to check when BigQuery query result returns zero records?

1 Answers