Modify impala__list_relations_without_caching macro implementation to…

… query each object type to return the object type (table / view) (#41)

Test plan:
1. Merge PR #33 to ensure new adpater test framework code is present.
2. Ensure pytest is installed
2. Run : python3 -m pytest tests/functional -k 'TestSimpleMaterializationsImpala' - This test should succeed.

dbt/adapters/impala/impl.py

@@ -128,23 +128,19 @@ def list_relations_without_caching(
 
         relations = []
         for row in results:
-            if len(row) != 1:
+            if len(row) != 2:
                 raise dbt.exceptions.RuntimeException(
                     f'Invalid value from "show table extended ...", '
                     f'got {len(row)} values, expected 4'
                 )
             _identifier = row[0]
-
-            # TODO: the following is taken from spark, needs to see what is there in impala
-            # TODO: this modification is not really right, need fix
-            rel_type = RelationType.View \
-                if 'view' in _identifier else RelationType.Table
+            _rel_type   = row[1]
 
             relation = self.Relation.create(
                 database=schema_relation.database,
                 schema=schema_relation.schema,
                 identifier=_identifier,
-                type=rel_type,
+                type=_rel_type,
                 information=_identifier,
             )
             relations.append(relation)

dbt/adapters/impala/relation.py

@@ -40,3 +40,13 @@ class ImpalaRelation(BaseRelation):
 
     def render(self):
         return super().render()
+
+    def new_copy(self, name, identifier):
+        new_relation = ImpalaRelation.create(
+                database=name,
+                schema=name,
+                identifier=identifier,
+                information=identifier,
+            )
+
+        return new_relation

dbt/include/impala/macros/adapters.sql

@@ -129,12 +129,24 @@
     {{ return(load_result('list_schemas').table) }}
 {% endmacro %}
 
+{# Note: This function currently needs to query each object to determine its type. Depending on the schema, this function could be expensive. #}
 {% macro impala__list_relations_without_caching(relation) %}
-  {% call statement('list_relations_without_caching', fetch_result=True) -%}
-    show tables in {{ relation }}
-  {% endcall %}
+  {% set result_set = run_query('show tables in ' ~ relation) %}
+  {% set objects_with_type = [] %}
+
+  {%- for rs in result_set -%}
+    {% set obj_type = [] %}
+
+    {% do obj_type.append(rs[0]) %}
+
+    {% set obj_rel = relation.new_copy(relation.schema, rs[0]) %}
+    {% set rel_type = get_relation_type(obj_rel) %}
+    {% do obj_type.append(rel_type) %}
+
+    {% do objects_with_type.append(obj_type) %}
+  {%- endfor -%}
 
-  {% do return(load_result('list_relations_without_caching').table) %}
+  {{ return(objects_with_type) }}
 {% endmacro %}
 
 {% macro impala__create_table_as(temporary, relation, sql) -%}