(#1687) no-op column expansion on Snowflake + BQ

core/dbt/include/global_project/macros/materializations/snapshot/snapshot.sql

@@ -217,6 +217,7 @@
 
       {% set staging_table = build_snapshot_staging_table(strategy, sql, target_relation) %}
 
+      -- this may no-op if the database does not require column expansion
       {% do adapter.expand_target_column_types(from_relation=staging_table,
                                                to_relation=target_relation) %}
 

plugins/bigquery/dbt/adapters/bigquery/impl.py

@@ -118,6 +118,10 @@ def expand_column_types(self, goal, current):
         # This is a no-op on BigQuery
         pass
 
+    def expand_target_column_types(self, from_relation, to_relation):
+        # This is a no-op on BigQuery
+        pass
+
     def list_relations_without_caching(self, information_schema, schema):
         connection = self.connections.get_thread_connection()
         client = connection.handle

plugins/snowflake/dbt/include/snowflake/macros/adapters.sql

@@ -90,3 +90,10 @@
     alter table {{ from_relation }} rename to {{ to_relation }}
   {%- endcall %}
 {% endmacro %}
+
+
+{% macro snowflake__alter_column_type(relation, column_name, new_column_type) -%}
+  {% call statement('alter_column_type') %}
+    alter table {{ relation }} alter {{ column_name }} set data type {{ new_column_type }};
+  {% endcall %}
+{% endmacro %}