(#2337) Handle array values in agate dataframe building

CHANGELOG.md

@@ -39,6 +39,7 @@
 - Fix "Object of type Decimal is not JSON serializable" error when BigQuery queries returned numeric types in nested data structures ([#2336](https://github.com/fishtown-analytics/dbt/issues/2336), [#2348](https://github.com/fishtown-analytics/dbt/pull/2348))
 - No longer query the information_schema.schemata view on bigquery ([#2320](https://github.com/fishtown-analytics/dbt/issues/2320), [#2382](https://github.com/fishtown-analytics/dbt/pull/2382))
 - Add support for `sql_header` config in incremental models ([#2136](https://github.com/fishtown-analytics/dbt/issues/2136), [#2200](https://github.com/fishtown-analytics/dbt/pull/2200))
+- Postgres array types can now be returned via `run_query` macro calls ([#2337](https://github.com/fishtown-analytics/dbt/issues/2337), [#2376](https://github.com/fishtown-analytics/dbt/pull/2376))
 
 ### Under the hood
 - Added more tests for source inheritance ([#2264](https://github.com/fishtown-analytics/dbt/issues/2264), [#2291](https://github.com/fishtown-analytics/dbt/pull/2291))

core/dbt/adapters/sql/connections.py

@@ -107,7 +107,10 @@ def get_result_from_cursor(cls, cursor: Any) -> agate.Table:
             rows = cursor.fetchall()
             data = cls.process_results(column_names, rows)
 
-        return dbt.clients.agate_helper.table_from_data(data, column_names)
+        return dbt.clients.agate_helper.table_from_data_flat(
+            data,
+            column_names
+        )
 
     def execute(
         self, sql: str, auto_begin: bool = False, fetch: bool = False

test/integration/060_run_query_tests/macros/test_pg_array_queries.sql

@@ -0,0 +1,16 @@
+
+{% macro test_array_results() %}
+
+    {% set sql %}
+        select ARRAY[1, 2, 3, 4] as mydata
+    {% endset %}
+
+    {% set result = run_query(sql) %}
+    {% set value = result.columns['mydata'][0] %}
+
+    {# This will be json-stringified #}
+    {% if value != "[1, 2, 3, 4]" %}
+        {% do exceptions.raise_compiler_error("Value was " ~ value) %}
+    {% endif %}
+
+{% endmacro %}

test/integration/060_run_query_tests/test_pg_types.py

@@ -0,0 +1,25 @@
+
+from test.integration.base import DBTIntegrationTest, use_profile
+import json
+
+class TestPostgresTypes(DBTIntegrationTest):
+
+    @property
+    def schema(self):
+        return "pg_query_types_060"
+
+    @property
+    def models(self):
+        return "models"
+
+    @property
+    def project_config(self):
+        return {
+            'config-version': 2,
+            'macro-paths': ['macros'],
+        }
+
+    @use_profile('postgres')
+    def test__postgres_nested_types(self):
+        result = self.run_dbt(['run-operation', 'test_array_results'])
+        self.assertTrue(result.success)