Check if a snowflake column exists before altering its comment (#3149)

* Check if column exists when altering column comments in snowflake

* Add new test class for persist docs models with missing columns

* Parallel run all integration tests after unit (#3328)

* don't clobber default args

* update changelog

* Update changelog for PR #3149

* Pull in upstream changes

Co-authored-by: Jeremy Cohen <jeremy@fishtownanalytics.com>
Co-authored-by: Kyle Wigley <kyle@fishtownanalytics.com>

CHANGELOG.md

@@ -4,6 +4,7 @@
 - Fix compiled sql for ephemeral models ([#3317](https://github.com/fishtown-analytics/dbt/issues/3317), [#3318](https://github.com/fishtown-analytics/dbt/pull/3318))
 - Now generating `run_results.json` even when no nodes are selected ([#3313](https://github.com/fishtown-analytics/dbt/issues/3313), [#3315](https://github.com/fishtown-analytics/dbt/pull/3315))
 - Stop clobbering default keyword arguments for jinja test definitions ([#3329](https://github.com/fishtown-analytics/dbt/issues/3329), [#3340](https://github.com/fishtown-analytics/dbt/pull/3340))
+- Update the snowflake adapter to only comment on a column if it exists when using the persist_docs config ([#3039](https://github.com/fishtown-analytics/dbt/issues/3039), [#3149](https://github.com/fishtown-analytics/dbt/pull/3149))
 
 ### Under the hood
 - Added logic for registry requests to raise a timeout error after a response hangs out for 30 seconds and 5 attempts have been made to reach the endpoint ([#3177](https://github.com/fishtown-analytics/dbt/issues/3177), [#3275](https://github.com/fishtown-analytics/dbt/pull/3275))
@@ -12,6 +13,7 @@ Contributors:
 - [@TeddyCr](https://github.com/TeddyCr) ([#3275](https://github.com/fishtown-analytics/dbt/pull/3275))
 - [@panasenco](https://github.com/panasenco) ([#3315](https://github.com/fishtown-analytics/dbt/pull/3315))
 - [@peiwangdb](https://github.com/peiwangdb) ([#3344](https://github.com/fishtown-analytics/dbt/pull/3344))
+- [@elikastelein](https://github.com/elikastelein) ([#3149](https://github.com/fishtown-analytics/dbt/pull/3149))
 
 ## dbt 0.20.0b1 (May 03, 2021)
 

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

@@ -155,9 +155,8 @@
 
 
 {% macro snowflake__alter_column_comment(relation, column_dict) -%}
-    alter {{ relation.type }} {{ relation }} alter
     {% for column_name in column_dict %}
-        {{ adapter.quote(column_name) if column_dict[column_name]['quote'] else column_name }} COMMENT $${{ column_dict[column_name]['description'] | replace('$', '[$]') }}$$ {{ ',' if not loop.last else ';' }}
+        comment if exists on column {{ relation }}.{{ adapter.quote(column_name) if column_dict[column_name]['quote'] else column_name }} is $${{ column_dict[column_name]['description'] | replace('$', '[$]') }}$$;
     {% endfor %}
 {% endmacro %}
 

test/integration/060_persist_docs_tests/models-column-missing/missing_column.sql

@@ -0,0 +1,2 @@
+{{ config(materialized='table') }}
+select 1 as id, 'Ed' as name

test/integration/060_persist_docs_tests/models-column-missing/schema.yml

@@ -0,0 +1,8 @@
+version: 2
+models:
+  - name: missing_column
+    columns:
+      - name: id
+        description: "test id column description"
+      - name: column_that_does_not_exist
+        description: "comment that cannot be created"

test/integration/060_persist_docs_tests/test_persist_docs.py

@@ -284,3 +284,38 @@ def test_bigquery_persist_docs(self):
 
             level_3_column = node['columns']['level_1.level_2.level_3_a']
             assert level_3_column['comment'] == "level_3 column description"
+
+
+class TestPersistDocsColumnMissing(BasePersistDocsTest):
+    @property
+    def project_config(self):
+        return {
+            'config-version': 2,
+            'models': {
+                'test': {
+                    '+persist_docs': {
+                        "columns": True,
+                    },
+                }
+            }
+        }
+
+    @property
+    def models(self):
+        return 'models-column-missing'
+
+    @use_profile('snowflake')
+    def test_snowflake_missing_column(self):
+        self.run_dbt()
+        self.run_dbt(['docs', 'generate'])
+        with open('target/catalog.json') as fp:
+            catalog_data = json.load(fp)
+        assert 'nodes' in catalog_data
+
+        table_node = catalog_data['nodes']['model.test.missing_column']
+        table_id_comment = table_node['columns']['ID']['comment']
+        assert table_id_comment.startswith('test id column description')
+
+    @use_profile('bigquery')
+    def test_bigquery_missing_column(self):
+        self.run_dbt()