feat(bigquery): add bigquery_query_iceberg_table sample to refresh and query an Apache Iceberg BigLake table

Problem:
The BigQuery documentation (https://cloud.google.com/bigquery/docs/query-iceberg-data)
needs a standalone, tested Python code sample demonstrating how to
refresh and query an Apache Iceberg BigLake table (region tag `bigquery_query_iceberg_table`).

Solution:
- Add `query_iceberg_table(project_id: str, dataset_id: str, table_id: str, connection_id: str, metadata_uri: str) -> None` in `bigquery/biglake/bigquery_query_iceberg_table.py`
  (Update an Apache Iceberg external table definition to point to the latest metadata snapshot on Cloud Storage and query its rows.)
- Add unit tests (`bigquery/biglake/bigquery_query_iceberg_table_test.py`) covering both the success
  path and API error handling (`GoogleAPICallError`)

Author: iennae

bigquery/biglake/bigquery_query_iceberg_table.py

@@ -0,0 +1,85 @@
+# 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_query_iceberg_table]
+import sys
+
+from google.api_core import exceptions
+from google.cloud import bigquery
+
+
+def query_iceberg_table(
+    project_id: str,
+    dataset_id: str,
+    table_id: str,
+    connection_id: str,
+    metadata_uri: str,
+) -> None:
+    """Refreshes an Apache Iceberg external table metadata snapshot and queries it.
+
+    Args:
+        project_id: Google Cloud project ID (for example, 'example-project').
+        dataset_id: BigQuery dataset ID containing the Iceberg external table
+            (for example, 'example_dataset').
+        table_id: BigQuery Iceberg external table ID
+            (for example, 'example_iceberg_table').
+        connection_id: Fully qualified BigQuery Cloud Resource connection ID
+            (for example, 'example-project.us.example_iceberg_conn').
+        metadata_uri: Cloud Storage URI of the Apache Iceberg metadata JSON file
+            (for example, 'gs://example-bucket/warehouse/db/table/metadata/v2.metadata.json').
+    """
+    client = bigquery.Client(project=project_id)
+    table_ref = f"{project_id}.{dataset_id}.{table_id}"
+    # BigQuery Iceberg external tables point to a specific Iceberg metadata JSON snapshot;
+    # re-running CREATE OR REPLACE EXTERNAL TABLE updates the snapshot URI with schema autodetection.
+    query = (
+        f"CREATE OR REPLACE EXTERNAL TABLE `{table_ref}` "
+        f"WITH CONNECTION `{connection_id}` "
+        "OPTIONS ("
+        "  format = 'ICEBERG',"
+        f"  uris = ['{metadata_uri}']"
+        "); "
+        "SELECT order_id, user_id, status, num_of_item "
+        f"FROM `{table_ref}` "
+        "ORDER BY order_id ASC;"
+    )
+
+    try:
+        print(f"Refreshing Iceberg metadata and querying table: {table_ref}")
+        query_job = client.query(query)
+        rows = list(query_job.result())
+    except exceptions.NotFound as err:
+        print(
+            f"error: Apache Iceberg table '{table_id}' in dataset '{dataset_id}' "
+            f"for project '{project_id}' (connection '{connection_id}', "
+            f"metadata '{metadata_uri}') was not found: {err.message}",
+            file=sys.stderr,
+        )
+        return
+    except exceptions.GoogleAPICallError as err:
+        print(
+            f"error: could not refresh or query Apache Iceberg table '{table_id}' "
+            f"in dataset '{dataset_id}' for project '{project_id}' "
+            f"(connection '{connection_id}', metadata '{metadata_uri}'): {err.message}",
+            file=sys.stderr,
+        )
+        return
+
+    print(f"Resource ID: {table_ref}")
+    print(f"Job ID: {query_job.job_id}")
+    print(f"Metadata URI: {metadata_uri}")
+    print(f"Rows Returned: {len(rows)}")
+
+
+# [END bigquery_query_iceberg_table]

bigquery/biglake/bigquery_query_iceberg_table_test.py

@@ -0,0 +1,76 @@
+# 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
+
+from google.api_core import exceptions
+import pytest
+
+import bigquery_query_iceberg_table
+
+
+def test_query_iceberg_table_success(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    mock_client = mock.MagicMock()
+    mock_job = mock.MagicMock()
+    mock_job.job_id = "example-job-123"
+    mock_job.statement_type = "SCRIPT"
+    mock_row = mock.MagicMock()
+    mock_job.result.return_value = [mock_row]
+    mock_client.query.return_value = mock_job
+    monkeypatch.setattr(
+        bigquery_query_iceberg_table.bigquery,
+        "Client",
+        lambda project=None: mock_client,
+    )
+
+    bigquery_query_iceberg_table.query_iceberg_table(
+        project_id="example-project",
+        dataset_id="example_dataset",
+        table_id="example_iceberg_table",
+        connection_id="example-project.us.example_iceberg_conn",
+        metadata_uri="gs://example-bucket/warehouse/orders_ns/customer_orders/metadata/v2.metadata.json",
+    )
+
+    captured = capsys.readouterr()
+    assert "Resource ID:" in captured.out
+    assert "example-project" in captured.out
+    assert mock_client.query.called
+
+
+def test_query_iceberg_table_error(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    mock_client = mock.MagicMock()
+    mock_client.query.side_effect = exceptions.NotFound("resource error")
+    monkeypatch.setattr(
+        bigquery_query_iceberg_table.bigquery,
+        "Client",
+        lambda project=None: mock_client,
+    )
+
+    bigquery_query_iceberg_table.query_iceberg_table(
+        project_id="example-project",
+        dataset_id="example_dataset",
+        table_id="example_iceberg_table",
+        connection_id="example-project.us.example_iceberg_conn",
+        metadata_uri="gs://example-bucket/warehouse/orders_ns/customer_orders/metadata/v2.metadata.json",
+    )
+
+    captured = capsys.readouterr()
+    assert "error:" in captured.err
+    assert "example-project" 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