Insert values of merge_exclude_columns when not matched

.changes/unreleased/Fixes-20230802-103350.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: Insert values of `merge_exclude_columns` when not matched
+time: 2023-08-02T10:33:50.107228-06:00
+custom:
+  Author: dbeatty10
+  Issue: "563"

dbt/include/redshift/macros/materializations/incremental_merge.sql

@@ -16,6 +16,7 @@
     {%- set merge_update_columns = config.get('merge_update_columns') -%}
     {%- set merge_exclude_columns = config.get('merge_exclude_columns') -%}
     {%- set update_columns = get_merge_update_columns(merge_update_columns, merge_exclude_columns, dest_columns) -%}
+    {%- set insert_columns = get_merge_update_columns(none, none, dest_columns) -%}
     {%- set sql_header = config.get('sql_header', none) -%}
 
     {% if unique_key %}
@@ -51,13 +52,13 @@
     {% endif %}
 
     when not matched then insert (
-        {% for column_name in update_columns -%}
+        {% for column_name in insert_columns -%}
             {{ column_name }}
             {%- if not loop.last %}, {% endif %}
         {% endfor %}
     )
     values (
-        {% for column_name in update_columns -%}
+        {% for column_name in insert_columns -%}
             DBT_INTERNAL_SOURCE.{{ column_name }}
             {%- if not loop.last %}, {% endif %}
         {% endfor %}

tests/functional/adapter/incremental/test_incremental_merge_exclude_columns.py

@@ -1,17 +1,7 @@
-import pytest
 from dbt.tests.adapter.incremental.test_incremental_merge_exclude_columns import (
     BaseMergeExcludeColumns,
 )
 
 
-seeds__expected_merge_exclude_columns_csv = """id,msg,color
-1,hello,blue
-2,goodbye,green
-3,NULL,purple
-"""
-
-
 class TestMergeExcludeColumns(BaseMergeExcludeColumns):
-    @pytest.fixture(scope="class")
-    def seeds(self):
-        return {"expected_merge_exclude_columns.csv": seeds__expected_merge_exclude_columns_csv}
+    pass