[WIP] - Upstream 16530 - Optimize HostList API: conditional DISTINCT + composite index on JobHostSummary

awx/api/views/__init__.py

@@ -1663,7 +1663,8 @@ def get_queryset(self):
         if filter_string:
             filter_qs = SmartFilter.query_from_string(filter_string)
             qs &= filter_qs
-        return qs.distinct().with_latest_summary_id()
+            qs = qs.distinct()
+        return qs.with_latest_summary_id()
 
     def list(self, *args, **kwargs):
         try:

awx/main/migrations/0201_jobhostsummary_main_jobhostsumm_host_id_desc.py

@@ -0,0 +1,17 @@
+# Generated by Django 5.2.15 on 2026-07-02 21:42
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0200_add_list_ordering'),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name='jobhostsummary',
+            index=models.Index(fields=['host', '-id'], name='main_jobhostsumm_host_id_desc'),
+        ),
+    ]

awx/main/models/jobs.py

@@ -1137,6 +1137,9 @@ class Meta:
         unique_together = [('job', 'host_name')]
         verbose_name_plural = _('job host summaries')
         ordering = ('-pk',)
+        indexes = [
+            models.Index(fields=['host', '-id'], name='main_jobhostsumm_host_id_desc'),
+        ]
 
     job = models.ForeignKey(
         'Job',