change: bring back indexes on SET_NULL foreign keys

While these are not used during normal operations, they are necessary
for UPDATE queries when deleting the content. Otherwise they end up as
full table scans.

docs/changes.rst

@@ -21,6 +21,7 @@ Not yet released.
 * Fixed some API URLs for categorized components.
 * Show plural form examples more prominently.
 * Highlight whitespace in :ref:`machine-translation`.
+* Faster comment and component removal.
 
 **Bug fixes**
 

weblate/trans/migrations/0005_alter_change_alert_alter_change_announcement_and_more.py

@@ -0,0 +1,63 @@
+# Copyright © Michal Čihař <[email protected]>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+# Generated by Django 4.2.5 on 2023-10-11 12:49
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("screenshots", "0001_squashed_weblate_5"),
+        ("trans", "0004_alter_change_action"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="change",
+            name="alert",
+            field=models.ForeignKey(
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="trans.alert",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="change",
+            name="announcement",
+            field=models.ForeignKey(
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="trans.announcement",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="change",
+            name="comment",
+            field=models.ForeignKey(
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="trans.comment",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="change",
+            name="screenshot",
+            field=models.ForeignKey(
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="screenshots.screenshot",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="change",
+            name="suggestion",
+            field=models.ForeignKey(
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="trans.suggestion",
+            ),
+        ),
+    ]

weblate/trans/models/change.py

@@ -534,23 +534,20 @@ class Change(models.Model, UserDisplayMixin):
         "Translation", null=True, on_delete=models.deletion.CASCADE, db_index=False
     )
     comment = models.ForeignKey(
-        "Comment", null=True, on_delete=models.deletion.SET_NULL, db_index=False
+        "Comment", null=True, on_delete=models.deletion.SET_NULL
     )
     suggestion = models.ForeignKey(
-        "Suggestion", null=True, on_delete=models.deletion.SET_NULL, db_index=False
+        "Suggestion", null=True, on_delete=models.deletion.SET_NULL
     )
     announcement = models.ForeignKey(
-        "Announcement", null=True, on_delete=models.deletion.SET_NULL, db_index=False
+        "Announcement", null=True, on_delete=models.deletion.SET_NULL
     )
     screenshot = models.ForeignKey(
         "screenshots.Screenshot",
         null=True,
         on_delete=models.deletion.SET_NULL,
-        db_index=False,
-    )
-    alert = models.ForeignKey(
-        "Alert", null=True, on_delete=models.deletion.SET_NULL, db_index=False
     )
+    alert = models.ForeignKey("Alert", null=True, on_delete=models.deletion.SET_NULL)
     user = models.ForeignKey(
         settings.AUTH_USER_MODEL, null=True, on_delete=models.deletion.CASCADE
     )