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.

Spanner Client#

Instantiating a Client#

To use the API, the Client class defines a high-level interface which handles authorization and creating other objects:

from import spanner
client = spanner.Client()

Long-lived Defaults#

When creating a Client, the user_agent and timeout_seconds arguments have sensible defaults (DEFAULT_USER_AGENT and DEFAULT_TIMEOUT_SECONDS). However, you may over-ride them and these will be used throughout all API requests made with the client you create.


  • For an overview of authentication in, see Authentication.

  • In addition to any authentication configuration, you can also set the GCLOUD_PROJECT environment variable for the Google Cloud Console project you’d like to interact with. If your code is running in Google App Engine or Google Compute Engine the project will be detected automatically. (Setting this environment variable is not required, you may instead pass the project explicitly when constructing a Client).

  • After configuring your environment, create a Client

    >>> from import spanner
    >>> client = spanner.Client()

    or pass in credentials and project explicitly

    >>> from import spanner
    >>> client = spanner.Client(project='my-project', credentials=creds)


Be sure to use the Project ID, not the Project Number.

Warnings about Multiprocessing#

  • When using multiprocessing, the application may hang if a instance is created before :class:multiprocessing.Pool or :class:multiprocessing.Process invokes :func:os.fork. The issue is under investigation, but may be only happening on Macintosh and not Linux. See GRPC/GRPC#12455 for more information.

Next Step#

After a Client, the next highest-level object is an Instance. You’ll need one before you can interact with databases.

Next, learn about the Instance Admin.


For a list of all google-cloud-spanner releases: