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pg_snippets.py
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pg_snippets.py
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#!/usr/bin/env python
# Copyright 2022 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 PostgreSql dialect.
For more information, see the README.rst under /spanner.
"""
import argparse
import base64
import datetime
import decimal
import time
from google.cloud import spanner, spanner_admin_database_v1
from google.cloud.spanner_admin_database_v1.types.common import DatabaseDialect
from google.cloud.spanner_v1 import param_types
from google.cloud.spanner_v1.data_types import JsonObject
OPERATION_TIMEOUT_SECONDS = 240
# [START spanner_postgresql_create_instance]
def create_instance(instance_id):
"""Creates an instance."""
spanner_client = spanner.Client()
config_name = "{}/instanceConfigs/regional-us-central1".format(
spanner_client.project_name
)
instance = spanner_client.instance(
instance_id,
configuration_name=config_name,
display_name="This is a display name.",
node_count=1,
labels={
"cloud_spanner_samples": "true",
"sample_name": "snippets-create_instance-explicit",
"created": str(int(time.time())),
},
)
operation = instance.create()
print("Waiting for operation to complete...")
operation.result(OPERATION_TIMEOUT_SECONDS)
print("Created instance {}".format(instance_id))
# [END spanner_postgresql_create_instance]
# [START spanner_postgresql_create_database]
def create_database(instance_id, database_id):
"""Creates a PostgreSql database and tables for sample data."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(
database_id,
database_dialect=DatabaseDialect.POSTGRESQL,
)
operation = database.create()
print("Waiting for operation to complete...")
operation.result(OPERATION_TIMEOUT_SECONDS)
create_table_using_ddl(database.name)
print("Created database {} on instance {}".format(database_id, instance_id))
def create_table_using_ddl(database_name):
spanner_client = spanner.Client()
request = spanner_admin_database_v1.UpdateDatabaseDdlRequest(
database=database_name,
statements=[
"""CREATE TABLE Singers (
SingerId bigint NOT NULL,
FirstName character varying(1024),
LastName character varying(1024),
SingerInfo bytea,
FullName character varying(2048)
GENERATED ALWAYS AS (FirstName || ' ' || LastName) STORED,
PRIMARY KEY (SingerId)
)""",
"""CREATE TABLE Albums (
SingerId bigint NOT NULL,
AlbumId bigint NOT NULL,
AlbumTitle character varying(1024),
PRIMARY KEY (SingerId, AlbumId)
) INTERLEAVE IN PARENT Singers ON DELETE CASCADE""",
],
)
operation = spanner_client.database_admin_api.update_database_ddl(request)
operation.result(OPERATION_TIMEOUT_SECONDS)
# [END spanner_postgresql_create_database]
# [START spanner_postgresql_insert_data]
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, "Marc", "Richards"),
(2, "Catalina", "Smith"),
(3, "Alice", "Trentor"),
(4, "Lea", "Martin"),
(5, "David", "Lomond"),
],
)
batch.insert(
table="Albums",
columns=("SingerId", "AlbumId", "AlbumTitle"),
values=[
(1, 1, "Total Junk"),
(1, 2, "Go, Go, Go"),
(2, 1, "Green"),
(2, 2, "Forever Hold Your Peace"),
(2, 3, "Terrified"),
],
)
print("Inserted data.")
# [END spanner_postgresql_insert_data]
# [START spanner_postgresql_delete_data]
def delete_data(instance_id, database_id):
"""Deletes sample data from the given database.
The database, table, and data must already exist and can be created using
`create_database` and `insert_data`.
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Delete individual rows
albums_to_delete = spanner.KeySet(keys=[[2, 1], [2, 3]])
# Delete a range of rows where the column key is >=3 and <5
singers_range = spanner.KeyRange(start_closed=[3], end_open=[5])
singers_to_delete = spanner.KeySet(ranges=[singers_range])
# Delete remaining Singers rows, which will also delete the remaining
# Albums rows because Albums was defined with ON DELETE CASCADE
remaining_singers = spanner.KeySet(all_=True)
with database.batch() as batch:
batch.delete("Albums", albums_to_delete)
batch.delete("Singers", singers_to_delete)
batch.delete("Singers", remaining_singers)
print("Deleted data.")
# [END spanner_postgresql_delete_data]
# [START spanner_postgresql_query_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)
with database.snapshot() as snapshot:
results = snapshot.execute_sql(
"SELECT SingerId, AlbumId, AlbumTitle FROM Albums"
)
for row in results:
print("SingerId: {}, AlbumId: {}, AlbumTitle: {}".format(*row))
# [END spanner_postgresql_query_data]
# [START spanner_postgresql_read_data]
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)
with database.snapshot() as snapshot:
keyset = spanner.KeySet(all_=True)
results = snapshot.read(
table="Albums", columns=("SingerId", "AlbumId", "AlbumTitle"), keyset=keyset
)
for row in results:
print("SingerId: {}, AlbumId: {}, AlbumTitle: {}".format(*row))
# [END spanner_postgresql_read_data]
# [START spanner_postgresql_add_column]
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 BIGINT"]
)
print("Waiting for operation to complete...")
operation.result(OPERATION_TIMEOUT_SECONDS)
print("Added the MarketingBudget column.")
# [END spanner_postgresql_add_column]
# [START spanner_postgresql_update_data]
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.")
# [END spanner_postgresql_update_data]
# [START spanner_postgresql_read_write_transaction]
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 < transfer_amount:
# 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.")
# [END spanner_postgresql_read_write_transaction]
# [START spanner_postgresql_query_data_with_new_column]
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)
with database.snapshot() as snapshot:
results = snapshot.execute_sql(
"SELECT SingerId, AlbumId, MarketingBudget FROM Albums"
)
for row in results:
print("SingerId: {}, AlbumId: {}, MarketingBudget: {}".format(*row))
# [END spanner_postgresql_query_data_with_new_column]
# [START spanner_postgresql_create_index]
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(OPERATION_TIMEOUT_SECONDS)
print("Added the AlbumsByAlbumTitle index.")
# [END spanner_postgresql_create_index]
# [START spanner_postgresql_read_data_with_index]
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)
with database.snapshot() as snapshot:
keyset = spanner.KeySet(all_=True)
results = snapshot.read(
table="Albums",
columns=("AlbumId", "AlbumTitle"),
keyset=keyset,
index="AlbumsByAlbumTitle",
)
for row in results:
print("AlbumId: {}, AlbumTitle: {}".format(*row))
# [END spanner_postgresql_read_data_with_index]
# [START spanner_postgresql_create_storing_index]
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)"
"INCLUDE (MarketingBudget)"
]
)
print("Waiting for operation to complete...")
operation.result(OPERATION_TIMEOUT_SECONDS)
print("Added the AlbumsByAlbumTitle2 index.")
# [END spanner_postgresql_create_storing_index]
# [START spanner_postgresql_read_data_with_storing_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_scoring_index` sample or by running this DDL statement
against your database:
CREATE INDEX AlbumsByAlbumTitle2 ON Albums(AlbumTitle)
INCLUDE (MarketingBudget)
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.snapshot() as snapshot:
keyset = spanner.KeySet(all_=True)
results = snapshot.read(
table="Albums",
columns=("AlbumId", "AlbumTitle", "MarketingBudget"),
keyset=keyset,
index="AlbumsByAlbumTitle2",
)
for row in results:
print("AlbumId: {}, AlbumTitle: {}, " "MarketingBudget: {}".format(*row))
# [END spanner_postgresql_read_data_with_storing_index]
# [START spanner_postgresql_read_only_transaction]
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(multi_use=True) 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("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("SingerId: {}, AlbumId: {}, AlbumTitle: {}".format(*row))
# [END spanner_postgresql_read_only_transaction]
def insert_with_dml(instance_id, database_id):
"""Inserts data with a DML statement into the database."""
# [START spanner_postgresql_dml_getting_started_insert]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def insert_singers(transaction):
row_ct = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES "
"(12, 'Melissa', 'Garcia'), "
"(13, 'Russell', 'Morales'), "
"(14, 'Jacqueline', 'Long'), "
"(15, 'Dylan', 'Shaw')"
)
print("{} record(s) inserted.".format(row_ct))
database.run_in_transaction(insert_singers)
# [END spanner_postgresql_dml_getting_started_insert]
def insert_with_dml_returning(instance_id, database_id):
"""Inserts sample data into the given database using a DML statement having a RETURNING clause."""
# [START spanner_postgresql_dml_insert_returning]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Insert records into the SINGERS table and returns the
# generated column FullName of the inserted records using
# 'RETURNING FullName'.
# It is also possible to return all columns of all the
# inserted records by using 'RETURNING *'.
def insert_singers(transaction):
results = transaction.execute_sql(
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES "
"(21, 'Luann', 'Chizoba'), "
"(22, 'Denis', 'Patricio'), "
"(23, 'Felxi', 'Ronan'), "
"(24, 'Dominik', 'Martyna') "
"RETURNING FullName"
)
for result in results:
print("FullName: {}".format(*result))
print("{} record(s) inserted.".format(results.stats.row_count_exact))
database.run_in_transaction(insert_singers)
# [END spanner_postgresql_dml_insert_returning]
def query_data_with_parameter(instance_id, database_id):
"""Queries sample data from the database using SQL with a parameter."""
# [START spanner_postgresql_query_with_parameter]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.snapshot() as snapshot:
results = snapshot.execute_sql(
"SELECT SingerId, FirstName, LastName FROM Singers " "WHERE LastName = $1",
params={"p1": "Garcia"},
param_types={"p1": spanner.param_types.STRING},
)
for row in results:
print("SingerId: {}, FirstName: {}, LastName: {}".format(*row))
# [END spanner_postgresql_query_with_parameter]
def write_with_dml_transaction(instance_id, database_id):
"""Transfers part of a marketing budget from one album to another."""
# [START spanner_postgresql_dml_getting_started_update]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def transfer_budget(transaction):
# Transfer marketing budget from one album to another. Performed in a
# single transaction to ensure that the transfer is atomic.
second_album_result = transaction.execute_sql(
"SELECT MarketingBudget from Albums " "WHERE SingerId = 2 and AlbumId = 2"
)
second_album_row = list(second_album_result)[0]
second_album_budget = second_album_row[0]
transfer_amount = 200000
# Transaction will only be committed if this condition still holds at
# the time of commit. Otherwise it will be aborted and the callable
# will be rerun by the client library
if second_album_budget >= transfer_amount:
first_album_result = transaction.execute_sql(
"SELECT MarketingBudget from Albums "
"WHERE SingerId = 1 and AlbumId = 1"
)
first_album_row = list(first_album_result)[0]
first_album_budget = first_album_row[0]
second_album_budget -= transfer_amount
first_album_budget += transfer_amount
# Update first album
transaction.execute_update(
"UPDATE Albums "
"SET MarketingBudget = $1 "
"WHERE SingerId = 1 and AlbumId = 1",
params={"p1": first_album_budget},
param_types={"p1": spanner.param_types.INT64},
)
# Update second album
transaction.execute_update(
"UPDATE Albums "
"SET MarketingBudget = $1 "
"WHERE SingerId = 2 and AlbumId = 2",
params={"p1": second_album_budget},
param_types={"p1": spanner.param_types.INT64},
)
print(
"Transferred {} from Album2's budget to Album1's".format(
transfer_amount
)
)
database.run_in_transaction(transfer_budget)
# [END spanner_postgresql_dml_getting_started_update]
# [START spanner_postgresql_read_stale_data]
def read_stale_data(instance_id, database_id):
"""Reads sample data from the database. The data is exactly 15 seconds
stale."""
import datetime
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
staleness = datetime.timedelta(seconds=15)
with database.snapshot(exact_staleness=staleness) as snapshot:
keyset = spanner.KeySet(all_=True)
results = snapshot.read(
table="Albums",
columns=("SingerId", "AlbumId", "MarketingBudget"),
keyset=keyset,
)
for row in results:
print("SingerId: {}, AlbumId: {}, MarketingBudget: {}".format(*row))
# [END spanner_postgresql_read_stale_data]
# [START spanner_postgresql_update_data_with_timestamp_column]
def update_data_with_timestamp(instance_id, database_id):
"""Updates Performances tables in the database with the COMMIT_TIMESTAMP
column.
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 BIGINT
In addition this update expects the LastUpdateTime column added by
applying this DDL statement against your database:
ALTER TABLE Albums ADD COLUMN LastUpdateTime SPANNER.COMMIT_TIMESTAMP
"""
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", "LastUpdateTime"),
values=[
(1, 1, 1000000, spanner.COMMIT_TIMESTAMP),
(2, 2, 750000, spanner.COMMIT_TIMESTAMP),
],
)
print("Updated data.")
# [END spanner_postgresql_update_data_with_timestamp_column]
# [START spanner_postgresql_add_timestamp_column]
def add_timestamp_column(instance_id, database_id):
"""Adds a new TIMESTAMP 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 LastUpdateTime SPANNER.COMMIT_TIMESTAMP"]
)
print("Waiting for operation to complete...")
operation.result(OPERATION_TIMEOUT_SECONDS)
print(
'Altered table "Albums" on database {} on instance {}.'.format(
database_id, instance_id
)
)
# [END spanner_postgresql_add_timestamp_column]
# [START spanner_postgresql_query_data_with_timestamp_column]
def query_data_with_timestamp(instance_id, database_id):
"""Queries sample data from the database using SQL.
This updates the `LastUpdateTime` column which must be created before
running this sample. You can add the column by running the
`add_timestamp_column` sample or by running this DDL statement
against your database:
ALTER TABLE Performances ADD COLUMN LastUpdateTime TIMESTAMP
OPTIONS (allow_commit_timestamp=true)
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.snapshot() as snapshot:
results = snapshot.execute_sql(
"SELECT SingerId, AlbumId, MarketingBudget FROM Albums "
"ORDER BY LastUpdateTime DESC"
)
for row in results:
print("SingerId: {}, AlbumId: {}, MarketingBudget: {}".format(*row))
# [END spanner_postgresql_query_data_with_timestamp_column]
# [START spanner_postgresql_create_table_with_timestamp_column]
def create_table_with_timestamp(instance_id, database_id):
"""Creates a table with a COMMIT_TIMESTAMP column."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
request = spanner_admin_database_v1.UpdateDatabaseDdlRequest(
database=database.name,
statements=[
"""CREATE TABLE Performances (
SingerId BIGINT NOT NULL,
VenueId BIGINT NOT NULL,
EventDate Date,
Revenue BIGINT,
LastUpdateTime SPANNER.COMMIT_TIMESTAMP NOT NULL,
PRIMARY KEY (SingerId, VenueId, EventDate))
INTERLEAVE IN PARENT Singers ON DELETE CASCADE"""
],
)
operation = spanner_client.database_admin_api.update_database_ddl(request)
print("Waiting for operation to complete...")
operation.result(OPERATION_TIMEOUT_SECONDS)
print(
"Created Performances table on database {} on instance {}".format(
database_id, instance_id
)
)
# [END spanner_postgresql_create_table_with_timestamp_column]
# [START spanner_postgresql_insert_data_with_timestamp_column]
def insert_data_with_timestamp(instance_id, database_id):
"""Inserts data with a COMMIT_TIMESTAMP field into a table."""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
with database.batch() as batch:
batch.insert(
table="Performances",
columns=("SingerId", "VenueId", "EventDate", "Revenue", "LastUpdateTime"),
values=[
(1, 4, "2017-10-05", 11000, spanner.COMMIT_TIMESTAMP),
(1, 19, "2017-11-02", 15000, spanner.COMMIT_TIMESTAMP),
(2, 42, "2017-12-23", 7000, spanner.COMMIT_TIMESTAMP),
],
)
print("Inserted data.")
# [END spanner_postgresql_insert_data_with_timestamp_column]
def insert_data_with_dml(instance_id, database_id):
"""Inserts sample data into the given database using a DML statement."""
# [START spanner_postgresql_dml_standard_insert]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def insert_singers(transaction):
row_ct = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) "
" VALUES (10, 'Virginia', 'Watson')"
)
print("{} record(s) inserted.".format(row_ct))
database.run_in_transaction(insert_singers)
# [END spanner_postgresql_dml_standard_insert]
def update_data_with_dml(instance_id, database_id):
"""Updates sample data from the database using a DML statement."""
# [START spanner_postgresql_dml_standard_update]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def update_albums(transaction):
row_ct = transaction.execute_update(
"UPDATE Albums "
"SET MarketingBudget = MarketingBudget * 2 "
"WHERE SingerId = 1 and AlbumId = 1"
)
print("{} record(s) updated.".format(row_ct))
database.run_in_transaction(update_albums)
# [END spanner_postgresql_dml_standard_update]
def update_data_with_dml_returning(instance_id, database_id):
"""Updates sample data from the database using a DML statement having a RETURNING clause."""
# [START spanner_postgresql_dml_update_returning]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Update MarketingBudget column for records satisfying
# a particular condition and returns the modified
# MarketingBudget column of the updated records using
# 'RETURNING MarketingBudget'.
# It is also possible to return all columns of all the
# updated records by using 'RETURNING *'.
def update_albums(transaction):
results = transaction.execute_sql(
"UPDATE Albums "
"SET MarketingBudget = MarketingBudget * 2 "
"WHERE SingerId = 1 and AlbumId = 1 "
"RETURNING MarketingBudget"
)
for result in results:
print("MarketingBudget: {}".format(*result))
print("{} record(s) updated.".format(results.stats.row_count_exact))
database.run_in_transaction(update_albums)
# [END spanner_postgresql_dml_update_returning]
def delete_data_with_dml(instance_id, database_id):
"""Deletes sample data from the database using a DML statement."""
# [START spanner_postgresql_dml_standard_delete]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def delete_singers(transaction):
row_ct = transaction.execute_update(
"DELETE FROM Singers WHERE FirstName = 'Alice'"
)
print("{} record(s) deleted.".format(row_ct))
database.run_in_transaction(delete_singers)
# [END spanner_postgresql_dml_standard_delete]
def delete_data_with_dml_returning(instance_id, database_id):
"""Deletes sample data from the database using a DML statement having a RETURNING clause."""
# [START spanner_postgresql_dml_delete_returning]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Delete records from SINGERS table satisfying a
# particular condition and returns the SingerId
# and FullName column of the deleted records using
# 'RETURNING SingerId, FullName'.
# It is also possible to return all columns of all the
# deleted records by using 'RETURNING *'.
def delete_singers(transaction):
results = transaction.execute_sql(
"DELETE FROM Singers WHERE FirstName = 'David' "
"RETURNING SingerId, FullName"
)
for result in results:
print("SingerId: {}, FullName: {}".format(*result))
print("{} record(s) deleted.".format(results.stats.row_count_exact))
database.run_in_transaction(delete_singers)
# [END spanner_postgresql_dml_delete_returning]
def dml_write_read_transaction(instance_id, database_id):
"""First inserts data then reads it from within a transaction using DML."""
# [START spanner_postgresql_dml_write_then_read]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def write_then_read(transaction):
# Insert record.
row_ct = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) "
" VALUES (11, 'Timothy', 'Campbell')"
)
print("{} record(s) inserted.".format(row_ct))
# Read newly inserted record.
results = transaction.execute_sql(
"SELECT FirstName, LastName FROM Singers WHERE SingerId = 11"
)
for result in results:
print("FirstName: {}, LastName: {}".format(*result))
database.run_in_transaction(write_then_read)
# [END spanner_postgresql_dml_write_then_read]
def update_data_with_partitioned_dml(instance_id, database_id):
"""Update sample data with a partitioned DML statement."""
# [START spanner_postgresql_dml_partitioned_update]
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)