Add indexes for user_management_user as larger instances struggle with slow queries

Author: Red-M

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Unify breadcrumbs behaviour with other Grafana Apps and main core ([#1906](https://github.com/grafana/oncall/issues/1906))
+- Added index on multiple columns in `user_management_user` table. This substantially speeds up queries used for showing the schedules of users.
+  By @Red_M ([#3054](https://github.com/grafana/oncall/pull/3054)).
 
 ## v1.3.38 (2023-09-19)
 

engine/apps/user_management/migrations/0015_auto_20230922_0540.py

@@ -0,0 +1,29 @@
+# Generated by Django 3.2.20 on 2023-09-22 05:40
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('user_management', '0014_auto_20230728_0802'),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name='user',
+            index=models.Index(fields=['organization', 'is_active', 'username', 'role'], name='user_manage_organiz_88c7db_idx'),
+        ),
+        migrations.AddIndex(
+            model_name='user',
+            index=models.Index(fields=['organization', 'is_active', 'email', 'role'], name='user_manage_organiz_696988_idx'),
+        ),
+        migrations.AddIndex(
+            model_name='user',
+            index=models.Index(fields=['username', 'organization', 'is_active', 'permissions'], name='user_manage_usernam_66f94c_idx'),
+        ),
+        migrations.AddIndex(
+            model_name='user',
+            index=models.Index(fields=['email', 'organization', 'is_active', 'permissions'], name='user_manage_email_c4f4fb_idx'),
+        ),
+    ]

engine/apps/user_management/models/user.py

@@ -169,6 +169,12 @@ class Meta:
         # Including is_active to unique_together and setting is_active to None allows to
         # have multiple deleted users with the same user_id, but user_id is unique among active users
         unique_together = ("user_id", "organization", "is_active")
+        indexes = [
+            models.Index(fields=["organization", "is_active", "username", "role"]),
+            models.Index(fields=["organization", "is_active", "email", "role"]),
+            models.Index(fields=["username", "organization", "is_active", "permissions"]),
+            models.Index(fields=["email", "organization", "is_active", "permissions"]),
+        ]
 
     public_primary_key = models.CharField(
         max_length=20,