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# Copyright 2019 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.
def client_query_relax_column(table_id: str) -> None:
# [START bigquery_relax_column_query_append]
from google.cloud import bigquery
# Construct a BigQuery client object.
client = bigquery.Client()
# TODO(developer): Set table_id to the ID of the destination table.
# table_id = "your-project.your_dataset.your_table_name"
# Retrieves the destination table and checks the number of required fields.
table = client.get_table(table_id) # Make an API request.
original_required_fields = sum(field.mode == "REQUIRED" for field in table.schema)
# In this example, the existing table has 2 required fields.
print("{} fields in the schema are required.".format(original_required_fields))
# Configures the query to append the results to a destination table,
# allowing field relaxation.
job_config = bigquery.QueryJobConfig(
destination=table_id,
schema_update_options=[bigquery.SchemaUpdateOption.ALLOW_FIELD_RELAXATION],
write_disposition=bigquery.WriteDisposition.WRITE_APPEND,
)
# Start the query, passing in the extra configuration.
client.query_and_wait(
# In this example, the existing table contains 'full_name' and 'age' as
# required columns, but the query results will omit the second column.
'SELECT "Beyonce" as full_name;',
job_config=job_config,
) # Make an API request and wait for job to complete
# Checks the updated number of required fields.
table = client.get_table(table_id) # Make an API request.
current_required_fields = sum(field.mode == "REQUIRED" for field in table.schema)
print("{} fields in the schema are now required.".format(current_required_fields))
# [END bigquery_relax_column_query_append]
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