feat(bigquery): add bigquery_read_biglake_gcs_storage_api sample to read a BigLake Cloud Storage table via BigQuery Storage Read API

Problem:
The BigQuery documentation (https://cloud.google.com/bigquery/docs/query-cloud-storage-using-biglake)
needs a standalone, tested Python code sample demonstrating how to
read a BigLake Cloud Storage table via BigQuery Storage Read API (region tag `bigquery_read_biglake_gcs_storage_api`).

Solution:
- Add `read_biglake_gcs_storage_api(project_id: str, dataset_id: str, table_id: str) -> None` in `bigquery/biglake/bigquery_read_biglake_gcs_storage_api.py`
  (Stream rows from a BigLake table backed by Cloud Storage using the BigQuery Storage Read API client.)
- Add unit tests (`bigquery/biglake/bigquery_read_biglake_gcs_storage_api_test.py`) covering both the success
  path and API error handling (`GoogleAPICallError`)

Author: iennae

bigquery/biglake/bigquery_read_biglake_gcs_storage_api.py

@@ -0,0 +1,83 @@
+# Copyright 2026 Google LLC
+#
+# 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
+#
+#     https://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.
+
+# [START bigquery_read_biglake_gcs_storage_api]
+import sys
+
+from google.api_core import exceptions
+from google.cloud import bigquery_storage_v1
+
+
+def read_biglake_gcs_storage_api(
+    project_id: str,
+    dataset_id: str,
+    table_id: str,
+) -> None:
+    """Reads projected columns from a BigLake table using the BigQuery Storage Read API.
+
+    Args:
+        project_id: Google Cloud project ID (for example, 'example-project').
+        dataset_id: BigQuery dataset ID containing the BigLake table
+            (for example, 'example_dataset').
+        table_id: BigLake table ID to read (for example, 'example_biglake_table').
+    """
+    client = bigquery_storage_v1.BigQueryReadClient()
+    parent = f"projects/{project_id}"
+    table_ref = f"projects/{project_id}/datasets/{dataset_id}/tables/{table_id}"
+
+    # Project specific columns in the ReadSession to minimize network transfer from Cloud Storage.
+    read_options = bigquery_storage_v1.types.ReadSession.TableReadOptions(
+        selected_fields=["id", "label", "score"]
+    )
+    requested_session = bigquery_storage_v1.types.ReadSession(
+        table=table_ref,
+        data_format=bigquery_storage_v1.types.DataFormat.AVRO,
+        read_options=read_options,
+    )
+    request = bigquery_storage_v1.types.CreateReadSessionRequest(
+        parent=parent,
+        read_session=requested_session,
+        max_stream_count=1,
+    )
+
+    try:
+        print(f"Creating Storage Read API session for BigLake table {table_ref}")
+        session = client.create_read_session(request=request)
+        rows_read = 0
+        if session.streams:
+            reader = client.read_rows(session.streams[0].name)
+            for response in reader:
+                rows_read += response.row_count
+    except exceptions.NotFound as err:
+        print(
+            f"error: BigLake table '{table_id}' not found in dataset '{dataset_id}' "
+            f"for project '{project_id}': {err.message}",
+            file=sys.stderr,
+        )
+        return
+    except exceptions.GoogleAPICallError as err:
+        print(
+            f"error: failed to read BigLake table '{table_id}' in dataset "
+            f"'{dataset_id}' for project '{project_id}': {err.message}",
+            file=sys.stderr,
+        )
+        return
+
+    print(f"Resource ID: {table_ref}")
+    print(f"Read Session: {session.name}")
+    print(f"Rows Read: {rows_read}")
+    print(f"Stream Count: {len(session.streams)}")
+
+
+# [END bigquery_read_biglake_gcs_storage_api]

bigquery/biglake/bigquery_read_biglake_gcs_storage_api_test.py

@@ -0,0 +1,79 @@
+# Copyright 2026 Google LLC
+#
+# 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
+#
+#     https://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.
+
+from unittest import mock
+
+import bigquery_read_biglake_gcs_storage_api
+from google.api_core import exceptions
+import pytest
+
+
+def test_read_biglake_gcs_storage_api_success(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    mock_client = mock.MagicMock()
+    mock_session = mock.MagicMock()
+    mock_session.name = "projects/example-project/locations/us/sessions/s1"
+    mock_stream = mock.MagicMock()
+    mock_stream.name = "projects/example-project/locations/us/sessions/s1/streams/0"
+    mock_session.streams = [mock_stream]
+    mock_client.create_read_session.return_value = mock_session
+
+    mock_response = mock.MagicMock()
+    mock_response.row_count = 3
+    mock_client.read_rows.return_value = [mock_response]
+
+    monkeypatch.setattr(
+        bigquery_read_biglake_gcs_storage_api.bigquery_storage_v1,
+        "BigQueryReadClient",
+        lambda: mock_client,
+    )
+
+    bigquery_read_biglake_gcs_storage_api.read_biglake_gcs_storage_api(
+        project_id="example-project",
+        dataset_id="example_dataset",
+        table_id="example_biglake_table",
+    )
+
+    captured = capsys.readouterr()
+    assert (
+        "Resource ID: projects/example-project/datasets/example_dataset/tables/example_biglake_table"
+        in captured.out
+    )
+    assert "Rows Read: 3" in captured.out
+    assert "Stream Count: 1" in captured.out
+
+
+def test_read_biglake_gcs_storage_api_error(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    mock_client = mock.MagicMock()
+    mock_client.create_read_session.side_effect = exceptions.NotFound("table not found")
+    monkeypatch.setattr(
+        bigquery_read_biglake_gcs_storage_api.bigquery_storage_v1,
+        "BigQueryReadClient",
+        lambda: mock_client,
+    )
+
+    bigquery_read_biglake_gcs_storage_api.read_biglake_gcs_storage_api(
+        project_id="example-project",
+        dataset_id="example_dataset",
+        table_id="example_biglake_table",
+    )
+
+    captured = capsys.readouterr()
+    assert "error:" in captured.err
+    assert "example_biglake_table" in captured.err

bigquery/biglake/noxfile_config.py

@@ -0,0 +1,23 @@
+# Copyright 2026 Google LLC
+#
+# 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
+#
+#     https://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.
+
+TEST_CONFIG_OVERRIDE = {
+    # You can opt out from the test for specific Python versions.
+    "ignored_versions": ["2.7", "3.7", "3.8", "3.9", "3.10", "3.11"],
+    # Enforce type hints on new samples.
+    "enforce_type_hints": True,
+    "gcloud_project_env": "GOOGLE_CLOUD_PROJECT",
+    "pip_version_override": None,
+    "envs": {},
+}

bigquery/biglake/requirements-test.txt

@@ -0,0 +1 @@
+pytest==9.0.3; python_version >= "3.10"

bigquery/biglake/requirements.txt

@@ -0,0 +1,2 @@
+google-cloud-bigquery==3.47.0
+google-cloud-bigquery-storage==2.43.0