Drop temp table if exists

.changes/unreleased/Fixes-20241108-154557.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: Cleans up the temp table created by the merge incremental stratergy when checking the schema
+time: 2024-11-08T15:45:57.570611Z
+custom:
+    Author: joshuao11
+    Issue: "1389"

dbt/include/bigquery/macros/materializations/incremental_strategy/merge.sql

@@ -27,8 +27,12 @@
         {% do predicates.append(avoid_require_partition_filter) %}
     {%- endif -%}
 
-    {% set build_sql = get_merge_sql(target_relation, source_sql, unique_key, dest_columns, predicates) %}
+    -- 1. Run merge statement
+    {{ get_merge_sql(target_relation, source_sql, unique_key, dest_columns, predicates) }};
 
-    {{ return(build_sql) }}
+    {% if tmp_relation_exists -%}
+    -- 2. clean up the temp table if we have used one
+      drop table if exists {{ tmp_relation }};
+    {%- endif -%}
 
 {% endmacro %}