added on_schema_change possibility (#426)

Co-authored-by: Noritaka Sekiyama <[email protected]>

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## New version
 - Fix session provisioning timeout and delay handling
+- Add on_schema_change possibility
 - Fix table materialization for Delta models
 
 ## v1.8.1

dbt/include/glue/macros/materializations/incremental/incremental.sql

@@ -11,21 +11,26 @@
     {%- set file_format = dbt_spark_validate_get_file_format(raw_file_format) -%}
     {%- set strategy = dbt_spark_validate_get_incremental_strategy(raw_strategy, file_format) -%}
   {% endif %}
+
   {%- set unique_key = config.get('unique_key', none) -%}
   {% if unique_key is none and file_format == 'hudi' %}
     {{ exceptions.raise_compiler_error("unique_key model configuration is required for HUDI incremental materializations.") }}
   {% endif %}
+
   {%- set partition_by = config.get('partition_by', none) -%}
   {%- set custom_location = config.get('custom_location', default='empty') -%}
   {%- set expire_snapshots = config.get('iceberg_expire_snapshots', 'True') -%}
   {%- set table_properties = config.get('table_properties', default='empty') -%}
 
   {% set target_relation = this %}
+  {%- set existing_relation = load_relation(this) -%}
   {% set existing_relation_type = adapter.get_table_type(target_relation)  %}
   {% set tmp_relation = make_temp_relation(target_relation, '_tmp') %}
   {% set is_incremental = 'False' %}
   {% set lf_tags_config = config.get('lf_tags_config') %}
   {% set lf_grants = config.get('lf_grants') %}
+  {%- set on_schema_change = incremental_validate_on_schema_change(config.get('on_schema_change'), default='ignore') -%}
+
   {% call statement() %}
     set spark.sql.autoBroadcastJoinThreshold=-1
   {% endcall %}
@@ -74,6 +79,8 @@
         {{ glue__create_tmp_table_as(tmp_relation, sql) }}
         {% set is_incremental = 'True' %}
         {% set build_sql = dbt_glue_get_incremental_sql(strategy, tmp_relation, target_relation, unique_key) %}
+
+        {%- do process_schema_changes(on_schema_change, tmp_relation, existing_relation) -%}
       {% endif %}
   {% endif %}