feat: Add SQL Server view materialization no-op optimization

Add get_view_definition_sql metadata macro for SQL Server views
Detect unchanged view definition and skip rebuild by using a no-op statement
Add test ensuring rerunning an unchanged view does not alter modify_date

Author: axellpadilla

dbt/include/sqlserver/macros/adapters/metadata.sql

@@ -90,6 +90,20 @@
   {{ return(load_result('get_relation_without_caching').table) }}
 {% endmacro %}
 
+{% macro get_view_definition_sql(relation) %}
+    {{ return(adapter.dispatch('get_view_definition_sql')(relation)) }}
+{% endmacro %}
+
+{% macro sqlserver__get_view_definition_sql(relation) -%}
+  {{ get_use_database_sql(relation.database) }}
+  select object_definition(v.object_id) as definition
+  from sys.views as v {{ information_schema_hints() }}
+  inner join sys.schemas as s {{ information_schema_hints() }}
+    on v.schema_id = s.schema_id
+  where upper(s.name) = upper('{{ relation.schema }}')
+    and upper(v.name) = upper('{{ relation.identifier }}')
+{% endmacro %}
+
 {% macro sqlserver__get_relation_last_modified(information_schema, relations) -%}
   {%- call statement('last_modified', fetch_result=True) -%}
         select

dbt/include/sqlserver/macros/materializations/models/view/view.sql

@@ -27,11 +27,29 @@
   -- grab current tables grants config for comparision later on
   {% set grant_config = config.get('grants') %}
   {% set preserved_grants = {} %}
+  {% set should_skip_view_update = false %}
+  {% set build_sql = none %}
 
   {% if existing_relation is not none and existing_relation.type != 'view' %}
     {% set current_grants_table = run_query(get_show_grant_sql(existing_relation)) %}
     {% set current_grants_dict = adapter.standardize_grants_dict(current_grants_table) %}
     {% set preserved_grants = diff_of_two_dicts(current_grants_dict, grant_config) %}
+    {% set build_sql = get_create_view_as_sql(intermediate_relation, sql) %}
+  {% elif existing_relation is not none and existing_relation.type == 'view' %}
+    {% set current_view_definition_table = run_query(get_view_definition_sql(existing_relation)) %}
+    {% if current_view_definition_table is not none and current_view_definition_table.rows | length > 0 %}
+      {% set normalized_relation = target_relation.include(database=False) | lower | replace('\n', '') | replace('\r', '') | replace('\t', '') | replace(' ', '') | replace(';', '') %}
+      {% set normalized_sql = sql | lower | replace('\n', '') | replace('\r', '') | replace('\t', '') | replace(' ', '') | replace(';', '') %}
+      {% set normalized_definition = current_view_definition_table.rows[0][0] | lower | replace('\n', '') | replace('\r', '') | replace('\t', '') | replace(' ', '') | replace(';', '') %}
+      {% set should_skip_view_update = normalized_definition.endswith(normalized_sql) %}
+    {% endif %}
+    {% if should_skip_view_update %}
+      {% set build_sql = 'declare @dbt_sqlserver_noop int;' %}
+    {% else %}
+      {% set build_sql = get_create_view_as_sql(target_relation, sql) %}
+    {% endif %}
+  {% else %}
+    {% set build_sql = get_create_view_as_sql(target_relation, sql) %}
   {% endif %}
 
   {{ run_hooks(pre_hooks, inside_transaction=False) }}
@@ -46,7 +64,7 @@
   {% if existing_relation is not none and existing_relation.type != 'view' %}
     -- build model
     {% call statement('main') -%}
-      {{ get_create_view_as_sql(intermediate_relation, sql) }}
+      {{ build_sql }}
     {%- endcall %}
 
     -- cleanup
@@ -60,7 +78,7 @@
   {% else %}
     -- build model
     {% call statement('main') -%}
-      {{ get_create_view_as_sql(target_relation, sql) }}
+      {{ build_sql }}
     {%- endcall %}
   {% endif %}
 

tests/functional/adapter/mssql/test_materialize_change.py

@@ -110,6 +110,44 @@ def test_public_select_grant_survives_swap(self, project):
         assert ("PUBLIC", "SELECT") in [(row[0].upper(), row[1].upper()) for row in grants]
 
 
+class TestViewMaterializationNoOp(BaseTableView):
+    """Test that rerunning an unchanged view avoids altering the view."""
+
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {"mat_object.sql": view_mat, "schema.yml": schema}
+
+    def test_unchanged_view_does_not_alter(self, project):
+        self.create_object(project, f"CREATE VIEW {project.test_schema}.mat_object AS {model_sql}")
+
+        before_modify_date = project.run_sql(
+            f"""
+            select modify_date
+            from sys.objects o
+            join sys.schemas s on o.schema_id = s.schema_id
+            where upper(s.name) = upper('{project.test_schema}')
+              and upper(o.name) = upper('mat_object')
+            """,
+            fetch="one",
+        )[0]
+
+        results = run_dbt(["run"])
+        assert len(results) == 1
+
+        after_modify_date = project.run_sql(
+            f"""
+            select modify_date
+            from sys.objects o
+            join sys.schemas s on o.schema_id = s.schema_id
+            where upper(s.name) = upper('{project.test_schema}')
+              and upper(o.name) = upper('mat_object')
+            """,
+            fetch="one",
+        )[0]
+
+        assert after_modify_date == before_modify_date
+
+
 class TestViewtoTable(BaseTableView):
     """Test if changing from a view object to a table object correctly replaces"""