Use common columns for incremental schema changes

dbt-labs · Nov 7, 2021 · 2bfde1e · 2bfde1e
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,7 +4,7 @@
 N/A
 
 ### Fixes
-N/A
+- When on_schema_change is set, pass common columns as dest_columns in incremental merge macros ([#4144](https://github.com/dbt-labs/dbt-core/issues/4144))
 
 ### Under the hood
 - Add optional profile parameters for atypical local connection setups ([#21](https://github.com/dbt-labs/dbt-snowflake/issues/21), [#36](https://github.com/dbt-labs/dbt-snowflake/pull/36))
@@ -19,6 +19,7 @@ N/A
 
 ### Contributors
 - [@NiallRees](https://github.com/NiallRees) ([#32](https://github.com/dbt-labs/dbt-snowflake/pull/32))
+- [@Kayrnt](https://github.com/Kayrnt) ([38](https://github.com/dbt-labs/dbt-snowflake/pull/38))
 
 ## dbt-snowflake v1.0.0b1 (October 11, 2021)
 

diff --git a/dbt/include/snowflake/macros/materializations/incremental.sql b/dbt/include/snowflake/macros/materializations/incremental.sql
@@ -58,8 +58,9 @@
     {% do adapter.expand_target_column_types(
            from_relation=tmp_relation,
            to_relation=target_relation) %}
-    {% do process_schema_changes(on_schema_change, tmp_relation, existing_relation) %}
-    {% set dest_columns = adapter.get_columns_in_relation(existing_relation) %}
+    {% set schema_changes_dict = process_schema_changes(on_schema_change, tmp_relation, existing_relation) %}
+    {#-- Destination columns is the intersection of source and target table --#}
+    {% set dest_columns = schema_changes_dict.get('in_target_and_source', existing_columns) %}
     {% set build_sql = dbt_snowflake_get_incremental_sql(strategy, tmp_relation, target_relation, unique_key, dest_columns) %}
 
   {% endif %}