CTAS if not exists

instead of doing "select 1" do a "create table if not exists ..."

Author: choyrim

dbt/include/trino/macros/adapters.sql

@@ -145,18 +145,20 @@
   {%- endif -%}
 {%- endmacro -%}
 
-{% macro trino__create_table_as(temporary, relation, sql, replace=False) -%}
+{% macro trino__create_table_as(temporary, relation, sql, on_exists=None) -%}
 
-  {%- if replace -%}
+  {%- set or_replace = '' -%}
+  {%- set if_not_exists = '' -%}
+  {%- if on_exists == 'replace' -%}
     {%- set or_replace = ' or replace' -%}
-  {%- else -%}
-    {%- set or_replace = '' -%}
+  {%- elif on_exists == 'skip' -%}
+    {%- set if_not_exists = ' if not exists' -%}
   {%- endif -%}
 
   {%- set contract_config = config.get('contract') -%}
   {%- if contract_config.enforced -%}
 
-  create{{ or_replace }} table
+  create{{ or_replace }} table{{ if_not_exists }}
     {{ relation }}
     {{ get_table_columns_and_constraints() }}
     {{ get_assert_columns_equivalent(sql) }}
@@ -173,14 +175,14 @@
 
   {%- else %}
 
-    create{{ or_replace }} table {{ relation }}
+    create{{ or_replace }} table{{ if_not_exists }} {{ relation }}
       {{ comment(model.get('description')) }}
       {{ properties(temporary) }}
     as (
       {{ sql }}
     );
 
-   {%- endif %}
+  {%- endif %}
 {% endmacro %}
 
 

dbt/include/trino/macros/materializations/table.sql

@@ -84,28 +84,14 @@
   {% elif on_table_exists == 'replace' %}
       {#-- build model #}
       {% call statement('main') -%}
-        {{ create_table_as(False, target_relation, sql, True) }}
+        {{ create_table_as(False, target_relation, sql, 'replace') }}
       {%- endcall %}
 
   {% elif on_table_exists == 'skip' %}
-
-      {#-- table does not exists #}
-      {% if existing_relation is none %}
-        {#-- build model #}
-        {% call statement('main') -%}
-          {{ create_table_as(False, target_relation, sql) }}
-        {%- endcall %}
-
-      {#-- table does exists #}
-      {% else %}
-        {#-- do nothing #}
-        {%- set log_message = 'table %s already exists. skipping.' % (existing_relation) -%}
-        {% do log(log_message) %}
-        {% call statement('main') -%}
-          select 1
-        {%- endcall %}
-
-      {% endif %}
+      {#-- build model #}
+      {% call statement('main') -%}
+        {{ create_table_as(False, target_relation, sql, 'skip') }}
+      {%- endcall %}
 
   {% endif %}
 {% endmacro %}

tests/functional/adapter/materialization/test_on_table_exists.py

@@ -106,13 +106,15 @@ def test_run_seed_test(self, project):
         results, logs = run_dbt_and_capture(["--debug", "run"], expect_pass=True)
         assert len(results) == 1
         assert (
-            f'create table "{project.database}"."{project.test_schema}"."materialization"' in logs
+            f'create table if not exists "{project.database}"."{project.test_schema}"."materialization"' in logs
         )
         assert "alter table" not in logs
         results, logs = run_dbt_and_capture(["--debug", "run"], expect_pass=True)
         assert len(results) == 1
         assert "drop table" not in logs
-        assert "create table" not in logs
+        assert (
+            f'create table if not exists "{project.database}"."{project.test_schema}"."materialization"' in logs
+        )
         # test tests
         results = run_dbt(["test"], expect_pass=True)
         assert len(results) == 3