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#!/usr/bin/env python
# Copyright 2016 Google, Inc.
#
# 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
#
# http://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.
"""This application demonstrates how to do basic operations using Cloud
Spanner.
For more information, see the README.rst under /spanner.
"""
import argparse
from google.cloud import spanner
def create_database(instance_id, database_id):
"""Creates a database and tables for sample data."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id, ddl_statements=[
"""CREATE TABLE Singers (
SingerId INT64 NOT NULL,
FirstName STRING(1024),
LastName STRING(1024),
SingerInfo BYTES(MAX)
) PRIMARY KEY (SingerId)""",
"""CREATE TABLE Albums (
SingerId INT64 NOT NULL,
AlbumId INT64 NOT NULL,
AlbumTitle STRING(MAX)
) PRIMARY KEY (SingerId, AlbumId),
INTERLEAVE IN PARENT Singers ON DELETE CASCADE"""
])
operation = database.create()
print('Waiting for operation to complete...')
operation.result()
print('Created database {} on instance {}'.format(
database_id, instance_id))
def insert_data(instance_id, database_id):
"""Inserts sample data into the given database.
The database and table must already exist and can be created using
`create_database`.
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.batch() as batch:
batch.insert(
table='Singers',
columns=('SingerId', 'FirstName', 'LastName',),
values=[
(1, u'Marc', u'Richards'),
(2, u'Catalina', u'Smith'),
(3, u'Alice', u'Trentor'),
(4, u'Lea', u'Martin'),
(5, u'David', u'Lomond')])
batch.insert(
table='Albums',
columns=('SingerId', 'AlbumId', 'AlbumTitle',),
values=[
(1, 1, u'Go, Go, Go'),
(1, 2, u'Total Junk'),
(2, 1, u'Green'),
(2, 2, u'Forever Hold Your Peace'),
(2, 3, u'Terrified')])
print('Inserted data.')
def query_data(instance_id, database_id):
"""Queries sample data from the database using SQL."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
results = database.execute_sql(
'SELECT SingerId, AlbumId, AlbumTitle FROM Albums')
for row in results:
print(u'SingerId: {}, AlbumId: {}, AlbumTitle: {}'.format(*row))
def read_data(instance_id, database_id):
"""Reads sample data from the database."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
keyset = spanner.KeySet(all_=True)
results = database.read(
table='Albums',
columns=('SingerId', 'AlbumId', 'AlbumTitle',),
keyset=keyset,)
for row in results:
print(u'SingerId: {}, AlbumId: {}, AlbumTitle: {}'.format(*row))
def query_data_with_new_column(instance_id, database_id):
"""Queries sample data from the database using SQL.
This sample uses the `MarketingBudget` column. You can add the column
by running the `add_column` sample or by running this DDL statement against
your database:
ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
results = database.execute_sql(
'SELECT SingerId, AlbumId, MarketingBudget FROM Albums')
for row in results:
print(u'SingerId: {}, AlbumId: {}, MarketingBudget: {}'.format(*row))
def add_index(instance_id, database_id):
"""Adds a simple index to the example database."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
operation = database.update_ddl([
'CREATE INDEX AlbumsByAlbumTitle ON Albums(AlbumTitle)'])
print('Waiting for operation to complete...')
operation.result()
print('Added the AlbumsByAlbumTitle index.')
def query_data_with_index(instance_id, database_id):
"""Queries sample data from the database using SQL and an index.
The index must exist before running this sample. You can add the index
by running the `add_index` sample or by running this DDL statement against
your database:
CREATE INDEX AlbumsByAlbumTitle ON Albums(AlbumTitle)
This sample also uses the `MarketingBudget` column. You can add the column
by running the `add_column` sample or by running this DDL statement against
your database:
ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
results = database.execute_sql(
"SELECT AlbumId, AlbumTitle, MarketingBudget "
"FROM Albums@{FORCE_INDEX=AlbumsByAlbumTitle} "
"WHERE AlbumTitle >= 'Ardvark' AND AlbumTitle < 'Goo'")
for row in results:
print(
u'AlbumId: {}, AlbumTitle: {}, '
'MarketingBudget: {}'.format(*row))
def read_data_with_index(instance_id, database_id):
"""Reads sample data from the database using an index.
The index must exist before running this sample. You can add the index
by running the `add_index` sample or by running this DDL statement against
your database:
CREATE INDEX AlbumsByAlbumTitle ON Albums(AlbumTitle)
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
keyset = spanner.KeySet(all_=True)
results = database.read(
table='Albums',
columns=('AlbumId', 'AlbumTitle'),
keyset=keyset,
index='AlbumsByAlbumTitle')
for row in results:
print('AlbumId: {}, AlbumTitle: {}'.format(*row))
def add_storing_index(instance_id, database_id):
"""Adds an storing index to the example database."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
operation = database.update_ddl([
'CREATE INDEX AlbumsByAlbumTitle2 ON Albums(AlbumTitle)'
'STORING (MarketingBudget)'])
print('Waiting for operation to complete...')
operation.result()
print('Added the AlbumsByAlbumTitle2 index.')
def read_data_with_storing_index(instance_id, database_id):
"""Reads sample data from the database using an index with a storing
clause.
The index must exist before running this sample. You can add the index
by running the `add_soring_index` sample or by running this DDL statement
against your database:
CREATE INDEX AlbumsByAlbumTitle2 ON Albums(AlbumTitle)
STORING (MarketingBudget)
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
keyset = spanner.KeySet(all_=True)
results = database.read(
table='Albums',
columns=('AlbumId', 'AlbumTitle', 'MarketingBudget'),
keyset=keyset,
index='AlbumsByAlbumTitle2')
for row in results:
print(
u'AlbumId: {}, AlbumTitle: {}, '
'MarketingBudget: {}'.format(*row))
def add_column(instance_id, database_id):
"""Adds a new column to the Albums table in the example database."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
operation = database.update_ddl([
'ALTER TABLE Albums ADD COLUMN MarketingBudget INT64'])
print('Waiting for operation to complete...')
operation.result()
print('Added the MarketingBudget column.')
def update_data(instance_id, database_id):
"""Updates sample data in the database.
This updates the `MarketingBudget` column which must be created before
running this sample. You can add the column by running the `add_column`
sample or by running this DDL statement against your database:
ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.batch() as batch:
batch.update(
table='Albums',
columns=(
'SingerId', 'AlbumId', 'MarketingBudget'),
values=[
(1, 1, 100000),
(2, 2, 500000)])
print('Updated data.')
def read_write_transaction(instance_id, database_id):
"""Performs a read-write transaction to update two sample records in the
database.
This will transfer 200,000 from the `MarketingBudget` field for the second
Album to the first Album. If the `MarketingBudget` is too low, it will
raise an exception.
Before running this sample, you will need to run the `update_data` sample
to populate the fields.
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def update_albums(transaction):
# Read the second album budget.
second_album_keyset = spanner.KeySet(keys=[(2, 2)])
second_album_result = transaction.read(
table='Albums', columns=('MarketingBudget',),
keyset=second_album_keyset, limit=1)
second_album_row = list(second_album_result)[0]
second_album_budget = second_album_row[0]
transfer_amount = 200000
if second_album_budget < 300000:
# Raising an exception will automatically roll back the
# transaction.
raise ValueError(
'The second album doesn\'t have enough funds to transfer')
# Read the first album's budget.
first_album_keyset = spanner.KeySet(keys=[(1, 1)])
first_album_result = transaction.read(
table='Albums', columns=('MarketingBudget',),
keyset=first_album_keyset, limit=1)
first_album_row = list(first_album_result)[0]
first_album_budget = first_album_row[0]
# Update the budgets.
second_album_budget -= transfer_amount
first_album_budget += transfer_amount
print(
'Setting first album\'s budget to {} and the second album\'s '
'budget to {}.'.format(
first_album_budget, second_album_budget))
# Update the rows.
transaction.update(
table='Albums',
columns=(
'SingerId', 'AlbumId', 'MarketingBudget'),
values=[
(1, 1, first_album_budget),
(2, 2, second_album_budget)])
database.run_in_transaction(update_albums)
print('Transaction complete.')
def read_only_transaction(instance_id, database_id):
"""Reads data inside of a read-only transaction.
Within the read-only transaction, or "snapshot", the application sees
consistent view of the database at a particular timestamp.
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.snapshot() as snapshot:
# Read using SQL.
results = snapshot.execute_sql(
'SELECT SingerId, AlbumId, AlbumTitle FROM Albums')
print('Results from first read:')
for row in results:
print(u'SingerId: {}, AlbumId: {}, AlbumTitle: {}'.format(*row))
# Perform another read using the `read` method. Even if the data
# is updated in-between the reads, the snapshot ensures that both
# return the same data.
keyset = spanner.KeySet(all_=True)
results = snapshot.read(
table='Albums',
columns=('SingerId', 'AlbumId', 'AlbumTitle',),
keyset=keyset,)
print('Results from second read:')
for row in results:
print(u'SingerId: {}, AlbumId: {}, AlbumTitle: {}'.format(*row))
if __name__ == '__main__':
parser = argparse.ArgumentParser(
description=__doc__,
formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument(
'instance_id', help='Your Cloud Spanner instance ID.')
parser.add_argument(
'--database-id', help='Your Cloud Spanner database ID.',
default='example_db')
subparsers = parser.add_subparsers(dest='command')
subparsers.add_parser('create_database', help=create_database.__doc__)
subparsers.add_parser('insert_data', help=insert_data.__doc__)
subparsers.add_parser('query_data', help=query_data.__doc__)
subparsers.add_parser('read_data', help=read_data.__doc__)
subparsers.add_parser('add_column', help=add_column.__doc__)
subparsers.add_parser('update_data', help=update_data.__doc__)
subparsers.add_parser(
'query_data_with_new_column', help=query_data_with_new_column.__doc__)
subparsers.add_parser(
'read_write_transaction', help=read_write_transaction.__doc__)
subparsers.add_parser(
'read_only_transaction', help=read_only_transaction.__doc__)
subparsers.add_parser('add_index', help=add_index.__doc__)
subparsers.add_parser('query_data_with_index', help=insert_data.__doc__)
subparsers.add_parser('read_data_with_index', help=insert_data.__doc__)
subparsers.add_parser('add_storing_index', help=add_storing_index.__doc__)
subparsers.add_parser(
'read_data_with_storing_index', help=insert_data.__doc__)
args = parser.parse_args()
if args.command == 'create_database':
create_database(args.instance_id, args.database_id)
elif args.command == 'insert_data':
insert_data(args.instance_id, args.database_id)
elif args.command == 'query_data':
query_data(args.instance_id, args.database_id)
elif args.command == 'read_data':
read_data(args.instance_id, args.database_id)
elif args.command == 'add_column':
add_column(args.instance_id, args.database_id)
elif args.command == 'update_data':
update_data(args.instance_id, args.database_id)
elif args.command == 'query_data_with_new_column':
query_data_with_new_column(args.instance_id, args.database_id)
elif args.command == 'read_write_transaction':
read_write_transaction(args.instance_id, args.database_id)
elif args.command == 'read_only_transaction':
read_only_transaction(args.instance_id, args.database_id)
elif args.command == 'add_index':
add_index(args.instance_id, args.database_id)
elif args.command == 'query_data_with_index':
query_data_with_index(args.instance_id, args.database_id)
elif args.command == 'read_data_with_index':
read_data_with_index(args.instance_id, args.database_id)
elif args.command == 'add_storing_index':
add_storing_index(args.instance_id, args.database_id)
elif args.command == 'read_data_with_storing_index':
read_data_with_storing_index(args.instance_id, args.database_id)