Python idiomatic client for Cloud Spanner.
- Documentation < 7349 /ul>
$ pip install --upgrade google-cloud-spannerFor more information on setting up your Python development environment,
such as installing pip and virtualenv on your system, please refer
to Python Development Environment Setup Guide for Google Cloud Platform.
With google-cloud-python we try to make authentication as painless as
possible. Check out the Authentication section in our documentation to
learn more. You may also find the authentication document shared by all
the google-cloud-* libraries to be helpful.
Cloud Spanner is the world’s first fully managed relational database service to offer both strong consistency and horizontal scalability for mission-critical online transaction processing (OLTP) applications. With Cloud Spanner you enjoy all the traditional benefits of a relational database; but unlike any other relational database service, Cloud Spanner scales horizontally to hundreds or thousands of servers to handle the biggest transactional workloads. (About Cloud Spanner)
Generally, to work with Cloud Spanner, you will want a transaction. The
preferred mechanism for this is to create a single function, which executes
as a callback to database.run_in_transaction:
# First, define the function that represents a single "unit of work"
# that should be run within the transaction.
def update_anniversary(transaction, person_id, unix_timestamp):
# The query itself is just a string.
#
# The use of @parameters is recommended rather than doing your
# own string interpolation; this provides protections against
# SQL injection attacks.
query = """SELECT anniversary FROM people
WHERE id = @person_id"""
# When executing the SQL statement, the query and parameters are sent
# as separate arguments. When using parameters, you must specify
# both the parameters themselves and their types.
row = transaction.execute_sql(
query=query,
params={'person_id': person_id},
param_types={
'person_id': types.INT64_PARAM_TYPE,
},
).one()
# Now perform an update on the data.
old_anniversary = row[0]
new_anniversary = _compute_anniversary(old_anniversary, years)
transaction.update(
'people',
['person_id', 'anniversary'],
[person_id, new_anniversary],
)
# Actually run the `update_anniversary` function in a transaction.
database.run_in_transaction(update_anniversary,
person_id=42,
unix_timestamp=1335020400,
)Once you have a transaction object (such as the first argument sent to
run_in_transaction), reading data is easy:
# Define a SELECT query.
query = """SELECT e.first_name, e.last_name, p.telephone
FROM employees as e, phones as p
WHERE p.employee_id == e.employee_id"""
# Execute the query and return results.
result = transaction.execute_sql(query)
for row in result.rows:
print(row)To add one or more records to a table, use insert:
transaction.insert(
'citizens',
columns=['email', 'first_name', 'last_name', 'age'],
values=[
['phred@exammple.com', 'Phred', 'Phlyntstone', 32],
['bharney@example.com', 'Bharney', 'Rhubble', 31],
],
)Transaction.update updates one or more existing records in a table. Fails
if any of the records does not already exist.
transaction.update(
'citizens',
columns=['email', 'age'],
values=[
['phred@exammple.com', 33],
['bharney@example.com', 32],
],
)See the google-cloud-python API Cloud Spanner documentation to learn how
to connect to Cloud Spanner using this Client Library.