from google.cloud import bigquery
from google.cloud.bigquery import SchemaField

gcclient = bigquery.Client()
dataset = gcclient.dataset("dataset_name")
gcschema = [
          SchemaField('field1', 'STRING', mode = 'required'),
          SchemaField('field2', 'STRING', mode = 'required'),
          SchemaField('field3', 'STRING', mode = 'required'),
          SchemaField('field4', 'STRING', mode = 'required'),
          SchemaField('field5', 'STRING', mode = 'required')
]
gctable = dataset.table("table_name", gcschema)
it = gctable.fetch_data() # Iterator is not in the order of table records