dbt snowflake/quote columns when altering (#1176)

Author: colin-rogers-dbt

dbt-snowflake/.changes/unreleased/Fixes-20250626-161248.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: quote columns when altering tables for incremental materialization
+time: 2025-06-26T16:12:48.423782-07:00
+custom:
+  Author: skadyan colin-rogers-dbt
+  Issue: "695"

dbt-snowflake/src/dbt/include/snowflake/macros/adapters.sql

@@ -170,7 +170,7 @@
     {% set sql -%}
        alter {{ relation.get_ddl_prefix_for_alter() }} {{ relation_type }} {{ relation.render() }} add column
           {% for column in add_columns %}
-            {{ column.name }} {{ column.data_type }}{{ ',' if not loop.last }}
+            {{ adapter.quote(column.name) }} {{ column.data_type }}{{ ',' if not loop.last }}
           {% endfor %}
     {%- endset -%}
 
@@ -183,7 +183,7 @@
     {% set sql -%}
         alter {{ relation.get_ddl_prefix_for_alter() }} {{ relation_type }} {{ relation.render() }} drop column
             {% for column in remove_columns %}
-                {{ column.name }}{{ ',' if not loop.last }}
+                {{ adapter.quote(column.name) }}{{ ',' if not loop.last }}
             {% endfor %}
     {%- endset -%}
 

dbt-snowflake/tests/functional/adapter/incremental/test_incremental_on_schema_change.py

@@ -1,7 +1,131 @@
 from dbt.tests.adapter.incremental.test_incremental_on_schema_change import (
     BaseIncrementalOnSchemaChange,
+    BaseIncrementalOnSchemaChangeSetup,
 )
+from dbt.tests.util import run_dbt
+import pytest
 
 
 class TestIncrementalOnSchemaChange(BaseIncrementalOnSchemaChange):
     pass
+
+
+# New fixtures for testing column names with spaces and special characters
+_MODEL_A_SPECIAL_COLUMNS = """
+{{
+    config(materialized='table')
+}}
+
+with source_data as (
+
+    select 1 as id, 'aaa' as "field with space", 'bbb' as "field-with-dash", 111 as "field@special", 'TTT' as "field.with.dots"
+    union all select 2 as id, 'ccc' as "field with space", 'ddd' as "field-with-dash", 222 as "field@special", 'UUU' as "field.with.dots"
+    union all select 3 as id, 'eee' as "field with space", 'fff' as "field-with-dash", 333 as "field@special", 'VVV' as "field.with.dots"
+    union all select 4 as id, 'ggg' as "field with space", 'hhh' as "field-with-dash", 444 as "field@special", 'WWW' as "field.with.dots"
+    union all select 5 as id, 'iii' as "field with space", 'jjj' as "field-with-dash", 555 as "field@special", 'XXX' as "field.with.dots"
+    union all select 6 as id, 'kkk' as "field with space", 'lll' as "field-with-dash", 666 as "field@special", 'YYY' as "field.with.dots"
+
+)
+
+select id
+       ,"field with space"
+       ,"field-with-dash"
+       ,"field@special"
+       ,"field.with.dots"
+
+from source_data
+"""
+
+_MODEL_INCREMENTAL_APPEND_NEW_COLUMNS_SPECIAL = """
+{{
+    config(
+        materialized='incremental',
+        unique_key='id',
+        on_schema_change='append_new_columns'
+    )
+}}
+
+WITH source_data AS (SELECT * FROM {{ ref('model_a_special_columns') }} )
+
+{% if is_incremental() %}
+
+SELECT id,
+       "field with space",
+       "field-with-dash",
+       "field@special",
+       "field.with.dots"
+FROM source_data WHERE id NOT IN (SELECT id from {{ this }} )
+
+{% else %}
+
+SELECT id,
+       "field with space",
+       "field-with-dash"
+FROM source_data where id <= 3
+
+{% endif %}
+"""
+
+_MODEL_INCREMENTAL_APPEND_NEW_COLUMNS_SPECIAL_TARGET = """
+{{
+    config(materialized='table')
+}}
+
+with source_data as (
+
+    select * from {{ ref('model_a_special_columns') }}
+
+)
+
+select id
+       ,"field with space"
+       ,"field-with-dash"
+       ,CASE WHEN id <= 3 THEN NULL ELSE "field@special" END AS "field@special"
+       ,CASE WHEN id <= 3 THEN NULL ELSE "field.with.dots" END AS "field.with.dots"
+
+from source_data
+"""
+
+
+class TestIncrementalOnSchemaChangeSpecialColumns(BaseIncrementalOnSchemaChangeSetup):
+    """Test incremental models with on_schema_change when column names contain spaces and special characters"""
+
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "model_a_special_columns.sql": _MODEL_A_SPECIAL_COLUMNS,
+            "incremental_append_new_columns_special.sql": _MODEL_INCREMENTAL_APPEND_NEW_COLUMNS_SPECIAL,
+            "incremental_append_new_columns_special_target.sql": _MODEL_INCREMENTAL_APPEND_NEW_COLUMNS_SPECIAL_TARGET,
+        }
+
+    def test_incremental_append_new_columns_with_special_characters(self, project):
+        """Test that incremental models with on_schema_change='append_new_columns' work correctly with column names containing spaces and special characters"""
+
+        # First run - creates initial table with id, "field with space", "field-with-dash"
+        run_dbt(
+            [
+                "run",
+                "--models",
+                "model_a_special_columns incremental_append_new_columns_special incremental_append_new_columns_special_target",
+            ]
+        )
+
+        # Second run - should append new columns "field@special" and "field.with.dots"
+        run_dbt(
+            [
+                "run",
+                "--models",
+                "model_a_special_columns incremental_append_new_columns_special incremental_append_new_columns_special_target",
+            ]
+        )
+
+        # Verify that the incremental model matches the target
+        from dbt.tests.util import check_relations_equal
+
+        check_relations_equal(
+            project.adapter,
+            [
+                "incremental_append_new_columns_special",
+                "incremental_append_new_columns_special_target",
+            ],
+        )