perf: use JOB_CREATION_OPTIONAL when allow_large_results=False (#1763)

Author: tswast

bigframes/session/clients.py

@@ -181,6 +181,13 @@ def _create_bigquery_client(self):
             location=self._location,
         )
 
+        # If a new enough client library is available, we opt-in to the faster
+        # backend behavior. This only affects code paths where query_and_wait is
+        # used, which doesn't expose a query job directly. See internal issue
+        # b/417985981.
+        if hasattr(bq_client, "default_job_creation_mode"):
+            bq_client.default_job_creation_mode = "JOB_CREATION_OPTIONAL"
+
         if self._bq_kms_key_name:
             # Note: Key configuration only applies automatically to load and query jobs, not copy jobs.
             encryption_config = bigquery.EncryptionConfiguration(

tests/unit/session/test_clients.py

@@ -46,6 +46,8 @@ def create_clients_provider(application_name: Optional[str] = None):
 def monkeypatch_client_constructors(monkeypatch):
     bqclient = mock.create_autospec(google.cloud.bigquery.Client)
     bqclient.return_value = bqclient
+    # Assume we have a new client library in the unit tests.
+    bqclient.default_job_creation_mode = None  # type: ignore
     monkeypatch.setattr(google.cloud.bigquery, "Client", bqclient)
 
     bqconnectionclient = mock.create_autospec(
@@ -83,6 +85,11 @@ def monkeypatch_client_constructors(monkeypatch):
     )
 
 
+def assert_bqclient_sets_default_job_creation_mode(provider: clients.ClientsProvider):
+    bqclient = provider.bqclient
+    assert bqclient.default_job_creation_mode == "JOB_CREATION_OPTIONAL"
+
+
 def assert_constructed_w_user_agent(mock_client: mock.Mock, expected_user_agent: str):
     assert (
         expected_user_agent