diff --git a/CHANGELOG.md b/CHANGELOG.md
index e92909a..39ba817 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 - In the `.quickstart.yml` file:
   - Adds `table_variables` for relevant sources to prevent missing sources from blocking downstream Quickstart models.
   - Adds `supported_vars` for Quickstart UI customization,
+- Adds the `partition_by_source_relation` macro to improve window function partition handling and prevent conflicts when the unioned data feature is disabled.
 
 # dbt_github v1.2.0
 [PR #75](https://github.com/fivetran/dbt_github/pull/75) includes the following updates:
diff --git a/macros/union/partition_by_source_relation.sql b/macros/union/partition_by_source_relation.sql
new file mode 100644
index 0000000..b233d91
--- /dev/null
+++ b/macros/union/partition_by_source_relation.sql
@@ -0,0 +1,15 @@
+{%- macro partition_by_source_relation(has_other_partitions='yes', alias=None) -%}
+
+{{ adapter.dispatch('partition_by_source_relation', 'github') () }}
+
+{%- endmacro %}
+
+{% macro default__partition_by_source_relation(has_other_partitions, alias) -%}
+    {% set prefix = '' if alias is none else alias ~ '.' %}
+
+    {%- if has_other_partitions == 'no' -%}
+        {{ 'partition by ' ~ prefix ~ 'source_relation' if var('github_sources', [])|length > 1 }}
+    {%- else -%}
+        {{ ', ' ~ prefix ~ 'source_relation' if var('github_sources', [])|length > 1 }}
+    {%- endif -%}
+{%- endmacro -%}
\ No newline at end of file
diff --git a/models/intermediate/int_github__issue_open_length.sql b/models/intermediate/int_github__issue_open_length.sql
index 4b77a93..05dc526 100644
--- a/models/intermediate/int_github__issue_open_length.sql
+++ b/models/intermediate/int_github__issue_open_length.sql
@@ -29,7 +29,7 @@ close_events_with_timestamps as (
     source_relation,
     issue_id,
     updated_at as valid_starting,
-    coalesce(lead(updated_at) over (partition by issue_id, source_relation order by updated_at), {{ dbt.current_timestamp() }}) as valid_until,
+    coalesce(lead(updated_at) over (partition by issue_id {{ github.partition_by_source_relation() }} order by updated_at), {{ dbt.current_timestamp() }}) as valid_until,
     is_closed
   from close_events_stacked
 )