# 2.0.0 Migration Guide The 2.0 release of the google-cloud-bigquery-storage client is a significant upgrade based on a next-gen code generator, and includes substantial interface changes. Existing code written for earlier versions of this library will likely require updates to use this version. This document describes the changes that have been made, and what you need to do to update your usage. If you experience issues or have questions, please file an issue.

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Supported Python Versions

WARNING: Breaking change

The 2.0.0 release requires Python 3.6+.

Import Path

The library’s top-level namespace is google.cloud.bigquery_storage. Importing from google.cloud.bigquery_storage_v1 still works, but it is advisable to use the google.cloud.bigquery_storage path in order to reduce the chance of future compatibility issues should the library be restuctured internally.

Before:

from google.cloud.bigquery_storage_v1 import BigQueryReadClient

After:

from google.cloud.bigquery_storage import BigQueryReadClient

Enum Types

WARNING: Breaking change

Enum types have been moved. Access them through the types module.

Before:

from google.cloud.bigquery_storage_v1 import enums

data_format = enums.DataFormat.ARROW

data_format = BigQueryReadClient.enums.DataFormat.ARROW

After:

from google.cloud.bigquery_storage import types

data_format = types.DataFormat.ARROW

Additionally, enums cannot be accessed through the client anymore. The following code wil not work:

data_format = BigQueryReadClient.enums.DataFormat.ARROW

Clients for Beta APIs

WARNING: Breaking change

Clients for beta APIs have been removed. The following import will not work:

from google.cloud.bigquery_storage_v1beta1 import BigQueryStorageClient
from google.cloud.bigquery_storage_v1beta2.gapic.big_query_read_client import BigQueryReadClient

The beta APIs are still available on the server side, but you will need to use the 1.x version of the library to access them.

Changed Default Value of the read_rows() Method’s metadata Argument

The client.read_rows() method does not accept None anymore as a valid value for the optional metadata argument. If not given, an empty tuple is used, but if you want to explicitly pass an “empty” value, you should use an empty tuple, too.

Before:

client.read_rows("stream_name", metadata=None)

After:

client.read_rows("stream_name", metadata=())

OR

client.read_rows("stream_name")

Method Calls

WARNING: Breaking change

Most of the client methods that send requests to the backend expect request objects. We provide a script that will convert most common use cases.

One exception to this is the BigQueryReadClient.read_rows() which is a hand-written wrapper around the auto-generated read_rows() method.

  • Install the library
python3 -m pip install google-cloud-bigquery-storage
  • The script fixup_bigquery_storage_v1_keywords.py is shipped with the library. It requires libcst to be installed. It expects an input directory (with the code to convert) and an empty destination directory.
$ fixup_bigquery_storage_v1_keywords.py --input-directory .samples/ --output-directory samples/

Before:

from google.cloud import bigquery_storage_v1

client = bigquery_storage_v1.BigQueryReadClient()

requested_session = bigquery_storage_v1.types.ReadSession()
requested_session.table = "projects/PROJECT_ID/datasets/DATASET_ID/tables/TABLE_ID"
requested_session.data_format = bigquery_storage_v1.enums.DataFormat.ARROW

session = client.create_read_session(
    "projects/parent_project",
    requested_session,
    max_stream_count=1,
)

After:

from google.cloud import bigquery_storage

client = bigquery_storage.BigQueryReadClient()

requested_session = bigquery_storage.types.ReadSession(
    table="projects/PROJECT_ID/datasets/DATASET_ID/tables/TABLE_ID",
    data_format=bigquery_storage.types.DataFormat.ARROW,
)
session = client.create_read_session(
    request={
        "parent": "projects/parent_project",
        "read_session": requested_session,
        "max_stream_count" 1,
    },
)

More Details

In google-cloud-bigquery-storage<2.0.0, parameters required by the API were positional parameters and optional parameters were keyword parameters.

Before:

def create_read_session(
    self,
    parent,
    read_session,
    max_stream_count=None,
    retry=google.api_core.gapic_v1.method.DEFAULT,
    timeout=google.api_core.gapic_v1.method.DEFAULT,
    metadata=None,
):

In the 2.0.0 release, methods that interact with the backend have a single positional parameter request. Method docstrings indicate whether a parameter is required or optional.

Some methods have additional keyword only parameters. The available parameters depend on the google.api.method_signature annotation specified by the API producer.

After:

def create_read_session(
    self,
    request: storage.CreateReadSessionRequest = None,
    *,
    parent: str = None,
    read_session: stream.ReadSession = None,
    max_stream_count: int = None,
    retry: retries.Retry = gapic_v1.method.DEFAULT,
    timeout: float = None,
    metadata: Sequence[Tuple[str, str]] = (),
) -> stream.ReadSession:

NOTE: The request parameter and flattened keyword parameters for the API are mutually exclusive. Passing both will result in an error.

Both of these calls are valid:

session = client.create_read_session(
    request={
        "parent": "projects/parent_project",
        "read_session": requested_session,
        "max_stream_count" 1,
    },
)
response = client.create_read_session(
    parent="projects/parent_project",
    read_session=requested_session,
    max_stream_count=1,
)

This call is invalid because it mixes request with a keyword argument max_stream_count. Executing this code will result in an error:

session = client.create_read_session(
    request={
        "parent": "projects/parent_project",
        "read_session": requested_session,
    },
    max_stream_count=1,
)

NOTE: The request parameter of some methods can also contain a more rich set of options that are otherwise not available as explicit keyword only parameters, thus these must be passed through request.

Removed Utility Methods

WARNING: Breaking change

Several utility methods such as project_path() and table_path() have been removed. These paths must now be constructed manually:

project_path = f"project/{PROJECT_ID}"
table_path = f"projects/{PROJECT_ID}/datasets/{DATASET_ID}/tables/{TABLE_ID}"

The two that remained are read_session_path() and read_stream_path().

Removed client_config and channel Parameter

The client cannot be constructed with channel or client_config arguments anymore, these deprecated parameters have been removed.

If you used client_config to customize retry and timeout settings for a particular method, you now need to do it upon method invocation by passing the custom timeout and retry arguments, respectively.