Avoid errors when missing column in yaml doc (#4285)

* Update postgres__alter_column_comment

* Update changelog

* Add integration test

CHANGELOG.md

@@ -1,9 +1,14 @@
 ## dbt-core 1.0.0rc2 (TBD)
 
+### Features
+- Avoid error when missing column in YAML description ([#4151](https://github.com/dbt-labs/dbt-core/issues/4151), [#4285](https://github.com/dbt-labs/dbt-core/pull/4285))
+
 ### Under the hood
 Add --indirect-selection parameter to profiles.yml and builtin DBT_ env vars; stringified parameter to enable multi-modal use ([#3997](https://github.com/dbt-labs/dbt-core/issues/3997), [PR #4270](https://github.com/dbt-labs/dbt-core/pull/4270))
 - Fix filesystem searcher test failure on Python 3.9 ([#3689](https://github.com/dbt-labs/dbt-core/issues/3689), [#4271](https://github.com/dbt-labs/dbt-core/pull/4271))
 
+Contributors:
+- [@kadero](https://github.com/kadero) ([#4285](https://github.com/dbt-labs/dbt-core/pull/4285))
 
 ## dbt-core 1.0.0rc1 (November 10, 2021)
 

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

@@ -180,7 +180,8 @@
 
 
 {% macro postgres__alter_column_comment(relation, column_dict) %}
-  {% for column_name in column_dict %}
+  {% set existing_columns = adapter.get_columns_in_relation(relation) | map(attribute="name") | list %}
+  {% for column_name in column_dict if (column_name in existing_columns) %}
     {% set comment = column_dict[column_name]['description'] %}
     {% set escaped_comment = postgres_escape_comment(comment) %}
     comment on column {{ relation }}.{{ adapter.quote(column_name) if column_dict[column_name]['quote'] else column_name }} is {{ escaped_comment }};

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.yaml

@@ -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

@@ -95,3 +95,32 @@ def run_has_comments_pglike(self):
     def test_postgres_comments(self):
         self.run_has_comments_pglike()
 
+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('postgres')
+    def test_postgres_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')