feat(bigquery): add bigquery_upgrade_manifest_biglake_table sample to upgrade a manifest external table to BigLake with automatic metadata caching

Problem:
The BigQuery documentation (https://cloud.google.com/bigquery/docs/query-open-table-format-using-manifest-files)
needs a standalone, tested Python code sample demonstrating how to
upgrade a manifest external table to BigLake with automatic metadata caching (region tag `bigquery_upgrade_manifest_biglake_table`).

Solution:
- Add `upgrade_manifest_biglake_table(project_id: str, dataset_id: str, table_id: str, connection_id: str, manifest_uri: str) -> None` in `bigquery/biglake/bigquery_upgrade_manifest_biglake_table.py`
  (Upgrade a manifest-backed external table to a BigLake table with AUTOMATIC metadata caching and connection binding.)
- Add unit tests (`bigquery/biglake/bigquery_upgrade_manifest_biglake_table_test.py`) covering both the success
  path and API error handling (`GoogleAPICallError`)

Author: iennae

bigquery/biglake/bigquery_upgrade_manifest_biglake_table.py

@@ -0,0 +1,96 @@
+# 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_upgrade_manifest_biglake_table]
+import sys
+
+from google.api_core import exceptions
+from google.cloud import bigquery
+
+
+def upgrade_manifest_biglake_table(
+    project_id: str,
+    dataset_id: str,
+    table_id: str,
+    connection_id: str,
+    manifest_uri: str,
+) -> None:
+    """Upgrades a manifest external table to a BigLake table with metadata caching.
+
+    Args:
+        project_id: Google Cloud project ID (for example, 'example-project').
+        dataset_id: BigQuery dataset ID containing the external table
+            (for example, 'example_dataset').
+        table_id: BigQuery external table ID to upgrade
+            (for example, 'example_manifest_table').
+        connection_id: Fully qualified BigQuery Cloud Resource connection ID
+            (for example, 'example-project.us.example_biglake_conn').
+        manifest_uri: Cloud Storage URI of the SymLinkTextInputFormat manifest file
+            (for example, 'gs://example-bucket/manifests/symlink.manifest').
+    """
+    client = bigquery.Client(project=project_id)
+    table_ref = f"{project_id}.{dataset_id}.{table_id}"
+    # Upgrading the manifest external table with a Cloud Resource connection and AUTOMATIC metadata
+    # caching accelerates open-table-format reads and enforces BigLake governance.
+    sql = f"""
+        CREATE OR REPLACE EXTERNAL TABLE `{table_ref}`
+        WITH CONNECTION `{connection_id}`
+        OPTIONS (
+          format = 'PARQUET',
+          uris = ['{manifest_uri}'],
+          file_set_spec_type = 'NEW_LINE_DELIMITED_MANIFEST',
+          max_staleness = INTERVAL 1 HOUR,
+          metadata_cache_mode = 'AUTOMATIC'
+        );
+        SELECT
+          id,
+          label,
+          score
+        FROM `{table_ref}`
+        ORDER BY id ASC
+        LIMIT 10;
+    """
+
+    try:
+        print(
+            f"Upgrading manifest external table to BigLake with metadata caching: {table_ref}"
+        )
+        query_job = client.query(sql)
+        rows = list(query_job.result())
+    except exceptions.NotFound as err:
+        print(
+            f"error: manifest external table '{table_id}' or connection '{connection_id}' "
+            f"not found in dataset '{dataset_id}' for project '{project_id}' "
+            f"(manifest '{manifest_uri}'): {err.message}",
+            file=sys.stderr,
+        )
+        return
+    except exceptions.GoogleAPICallError as err:
+        print(
+            f"error: failed to upgrade manifest external table '{table_id}' in dataset "
+            f"'{dataset_id}' for project '{project_id}' (connection '{connection_id}', "
+            f"manifest '{manifest_uri}'): {err.message}",
+            file=sys.stderr,
+        )
+        return
+
+    print(f"Resource ID: {table_ref}")
+    print(f"Connection ID: {connection_id}")
+    print(f"Job ID: {query_job.job_id}")
+    print(f"Manifest URI: {manifest_uri}")
+    print("Metadata Cache Mode: AUTOMATIC")
+    print(f"Rows Returned: {len(rows)}")
+
+
+# [END bigquery_upgrade_manifest_biglake_table]

bigquery/biglake/bigquery_upgrade_manifest_biglake_table_test.py

@@ -0,0 +1,71 @@
+# 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_upgrade_manifest_biglake_table
+from google.api_core import exceptions
+import pytest
+
+
+def test_upgrade_manifest_biglake_table_success(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    with mock.patch("google.cloud.bigquery.Client") as mock_client_cls:
+        mock_client = mock_client_cls.return_value
+        mock_job = mock.MagicMock()
+        mock_job.job_id = "example-job-123"
+        mock_job.result.return_value = [
+            mock.MagicMock(),
+            mock.MagicMock(),
+            mock.MagicMock(),
+        ]
+        mock_client.query.return_value = mock_job
+
+        bigquery_upgrade_manifest_biglake_table.upgrade_manifest_biglake_table(
+            project_id="example-project",
+            dataset_id="example_dataset",
+            table_id="example_manifest_table",
+            connection_id="example-project.us.example_biglake_conn",
+            manifest_uri="gs://example-bucket/manifests/symlink.manifest",
+        )
+
+        mock_client.query.assert_called_once()
+        captured = capsys.readouterr()
+        assert (
+            "Resource ID: example-project.example_dataset.example_manifest_table"
+            in captured.out
+        )
+        assert "Metadata Cache Mode: AUTOMATIC" in captured.out
+        assert "Rows Returned: 3" in captured.out
+
+
+def test_upgrade_manifest_biglake_table_not_found(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    with mock.patch("google.cloud.bigquery.Client") as mock_client_cls:
+        mock_client = mock_client_cls.return_value
+        mock_client.query.side_effect = exceptions.NotFound("Connection not found")
+
+        bigquery_upgrade_manifest_biglake_table.upgrade_manifest_biglake_table(
+            project_id="example-project",
+            dataset_id="example_dataset",
+            table_id="example_manifest_table",
+            connection_id="example-project.us.example_biglake_conn",
+            manifest_uri="gs://example-bucket/manifests/symlink.manifest",
+        )
+
+        captured = capsys.readouterr()
+        assert "error:" in captured.err
+        assert "example_manifest_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