Add index to activity table

src/sentry/migrations/0996_add_activity_group_datetime_index.py

@@ -0,0 +1,35 @@
+# Generated by Django 5.2.1 on 2025-10-03 00:00
+
+from django.db import migrations, models
+
+from sentry.new_migrations.migrations import CheckedMigration
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production.
+    # This should only be used for operations where it's safe to run the migration after your
+    # code has deployed. So this should not be used for most operations that alter the schema
+    # of a table.
+    # Here are some things that make sense to mark as post deployment:
+    # - Large data migrations. Typically we want these to be run manually so that they can be
+    #   monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   run this outside deployments so that we don't block them. Note that while adding an index
+    #   is a schema change, it's completely safe to run the operation after the code has deployed.
+    # Once deployed, run these manually via: https://develop.sentry.dev/database-migrations/#migration-deployment
+
+    is_post_deployment = True
+
+    dependencies = [
+        ("sentry", "0995_add_date_updated_to_grouphash_metadata"),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name="activity",
+            index=models.Index(
+                fields=["group_id", "datetime"],
+                name="sentry_activity_group_datetime_idx",
+            ),
+        ),
+    ]

src/sentry/models/activity.py

@@ -129,7 +129,10 @@ class Activity(Model):
     class Meta:
         app_label = "sentry"
         db_table = "sentry_activity"
-        indexes = (models.Index(fields=("project", "datetime")),)
+        indexes = (
+            models.Index(fields=("project", "datetime")),
+            models.Index(fields=("group_id", "datetime")),
+        )
 
     __repr__ = sane_repr("project_id", "group_id", "event_id", "user_id", "type", "ident")