fix: access MATERIALIZED_VIEW with read_gbq (#1070)

* fix: corrected inability to access MATERIALIZED_VIEW with read_gbq * update test

Author: Genesis929

bigframes/core/nodes.py

@@ -547,7 +547,7 @@ class GbqTable:
  table_id: str = field()
  physical_schema: Tuple[bq.SchemaField, ...] = field()
  n_rows: int = field()
- is_physical_table: bool = field()
+ is_physically_stored: bool = field()
  cluster_cols: typing.Optional[Tuple[str, ...]]
 
  @staticmethod
@@ -563,7 +563,7 @@ def from_table(table: bq.Table, columns: Sequence[str] = ()) -> GbqTable:
  table_id=table.table_id,
  physical_schema=schema,
  n_rows=table.num_rows,
- is_physical_table=(table.table_type == "TABLE"),
+ is_physically_stored=(table.table_type in ["TABLE", "MATERIALIZED_VIEW"]),
  cluster_cols=None
  if table.clustering_fields is None
  else tuple(table.clustering_fields),
@@ -641,7 +641,7 @@ def variables_introduced(self) -> int:
 
  @property
  def row_count(self) -> typing.Optional[int]:
- if self.source.sql_predicate is None and self.source.table.is_physical_table:
+ if self.source.sql_predicate is None and self.source.table.is_physically_stored:
  return self.source.table.n_rows
  return None
 

bigframes/session/_io/bigquery/read_gbq_table.py

@@ -102,6 +102,7 @@ def validate_table(
  table_ref: bigquery.table.TableReference,
  columns: Optional[Sequence[str]],
  snapshot_time: datetime.datetime,
+ table_type: str,
  filter_str: Optional[str] = None,
 ) -> bool:
  """Validates that the table can be read, returns True iff snapshot is supported."""
@@ -124,6 +125,17 @@ def validate_table(
  if table_ref.dataset_id.startswith("_"):
  return False
 
+ # Materialized views，does not support snapshot
+ if table_type == "MATERIALIZED_VIEW":
+ warnings.warn(
+ "Materialized views do not support FOR SYSTEM_TIME AS OF queries. "
+ "Attempting query without time travel. Be aware that as materialized views "
+ "are updated periodically, modifications to the underlying data in the view may "
+ "result in errors or unexpected behavior.",
+ category=bigframes.exceptions.TimeTravelDisabledWarning,
+ )
+ return False
+
  # Second, try with snapshot to verify table supports this feature
  snapshot_sql = bigframes.session._io.bigquery.to_query(
  query_or_table=f"{table_ref.project}.{table_ref.dataset_id}.{table_ref.table_id}",

bigframes/session/loader.py

@@ -339,7 +339,12 @@ def read_gbq_table(
  )
 
  enable_snapshot = enable_snapshot and bf_read_gbq_table.validate_table(
- self._bqclient, table_ref, all_columns, time_travel_timestamp, filter_str
+ self._bqclient,
+ table_ref,
+ all_columns,
+ time_travel_timestamp,
+ table.table_type,
+ filter_str,
  )
 
  # ----------------------------

tests/system/small/test_dataframe.py

@@ -1524,6 +1524,10 @@ def test_shape(scalars_dfs):
 @pytest.mark.parametrize(
  "reference_table, test_table",
  [
+ (
+ "bigframes-dev.bigframes_tests_sys.base_table",
+ "bigframes-dev.bigframes_tests_sys.base_table_mat_view",
+ ),
  (
  "bigframes-dev.bigframes_tests_sys.base_table",
  "bigframes-dev.bigframes_tests_sys.base_table_view",

tests/system/small/test_session.py

@@ -390,9 +390,16 @@ def test_read_gbq_twice_with_same_timestamp(session, penguins_table_id):
  assert df3 is not None
 
 
-def test_read_gbq_on_linked_dataset_warns(session):
+@pytest.mark.parametrize(
+ "source_table",
+ [
+ "bigframes-dev.thelook_ecommerce.orders",
+ "bigframes-dev.bigframes_tests_sys.base_table_mat_view",
+ ],
+)
+def test_read_gbq_on_linked_dataset_warns(session, source_table):
  with warnings.catch_warnings(record=True) as warned:
- session.read_gbq("bigframes-dev.thelook_ecommerce.orders")
+ session.read_gbq(source_table)
  assert len(warned) == 1
  assert warned[0].category == bigframes.exceptions.TimeTravelDisabledWarning