ADAP-1017: Fix configuration change monitoring for scenarios with no changes (#1009)

* changie
* add a test demonstrating the issue
* check that the change collection has changes instead of checking that it exists
* remove the partition config value from the config change since it is not hashable

Author: mikealfare

.changes/unreleased/Fixes-20231107-174352.yaml

@@ -0,0 +1,7 @@
+kind: Fixes
+body: Fixed issue where materialized views were failing on re-run with minimal config
+  parameters
+time: 2023-11-07T17:43:52.972135-05:00
+custom:
+  Author: "mikealfare"
+  Issue: "1007"

dbt/adapters/bigquery/relation.py

@@ -84,9 +84,10 @@ def materialized_view_config_changeset(
             )
 
         if new_materialized_view.partition != existing_materialized_view.partition:
+            # the existing PartitionConfig is not hashable, but since we need to do
+            # a full refresh either way, we don't need to provide a context
             config_change_collection.partition = BigQueryPartitionConfigChange(
                 action=RelationConfigChangeAction.alter,
-                context=new_materialized_view.partition,
             )
 
         if new_materialized_view.cluster != existing_materialized_view.cluster:
@@ -95,7 +96,7 @@ def materialized_view_config_changeset(
                 context=new_materialized_view.cluster,
             )
 
-        if config_change_collection:
+        if config_change_collection.has_changes:
             return config_change_collection
         return None
 

dbt/adapters/bigquery/relation_configs/_partition.py

@@ -152,7 +152,7 @@ def parse_bq_table(cls, table: BigQueryTable) -> Dict[str, Any]:
 
 @dataclass(frozen=True, eq=True, unsafe_hash=True)
 class BigQueryPartitionConfigChange(RelationConfigChange):
-    context: Optional[PartitionConfig]
+    context: Optional[Any] = None
 
     @property
     def requires_full_refresh(self) -> bool:

tests/functional/adapter/materialized_view_tests/_files.py

@@ -67,3 +67,14 @@
     record_valid_date
 from {{ ref('my_seed') }}
 """
+
+
+MY_MINIMAL_MATERIALIZED_VIEW = """
+{{
+  config(
+    materialized = 'materialized_view',
+    )
+}}
+
+select * from {{ ref('my_seed') }}
+"""

tests/functional/adapter/materialized_view_tests/test_materialized_view.py

@@ -4,6 +4,7 @@
 from dbt.tests.adapter.materialized_view.basic import MaterializedViewBasic
 
 from tests.functional.adapter.materialized_view_tests._mixin import BigQueryMaterializedViewMixin
+from tests.functional.adapter.materialized_view_tests import _files
 
 
 class TestBigqueryMaterializedViewsBasic(BigQueryMaterializedViewMixin, MaterializedViewBasic):
@@ -27,3 +28,26 @@ def test_materialized_view_only_updates_after_refresh(
         self, project, my_materialized_view, my_seed
     ):
         pass
+
+
+class TestMaterializedViewRerun:
+    """
+    This addresses: https://github.com/dbt-labs/dbt-bigquery/issues/1007
+
+    This effectively tests that defaults get properly set so that the run is idempotent.
+    If the defaults are not properly set, changes could appear when there are no changes
+    and cause unexpected scenarios.
+    """
+
+    @pytest.fixture(scope="class", autouse=True)
+    def models(self):
+        return {"my_minimal_materialized_view.sql": _files.MY_MINIMAL_MATERIALIZED_VIEW}
+
+    @pytest.fixture(scope="class", autouse=True)
+    def seeds(self):
+        return {"my_seed.csv": _files.MY_SEED}
+
+    def test_minimal_materialized_view_is_idempotent(self, project):
+        run_dbt(["seed"])
+        run_dbt(["run"])
+        run_dbt(["run"])