snapshot of https://github.com/zulip/zulip.git @ 48c69911c7dd4e03b20552eb3bd77ad8151c1357 (2026-09-15)

zerver/migrations/0772_clean_up_imageattachments.py

@@ -0,0 +1,60 @@
+from django.db import connection, migrations
+from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+from django.db.models import Exists, OuterRef
+from psycopg2.sql import SQL, Identifier
+
+
+def delete_unattached_imageattachments(
+    apps: StateApps, schema_editor: BaseDatabaseSchemaEditor
+) -> None:
+    ArchivedAttachment = apps.get_model("zerver", "ArchivedAttachment")
+    Attachment = apps.get_model("zerver", "Attachment")
+    ImageAttachment = apps.get_model("zerver", "ImageAttachment")
+
+    table = ImageAttachment._meta.db_table
+    with connection.cursor() as cursor:
+        cursor.execute(SQL("SELECT MIN(id), MAX(id) FROM {}").format(Identifier(table)))
+        (min_id, max_id) = cursor.fetchone()
+        if min_id is None:
+            return
+
+        q = ImageAttachment.objects.alias(
+            has_attachment=Exists(Attachment.objects.filter(path_id=OuterRef("path_id"))),
+            has_archived_attachment=Exists(
+                ArchivedAttachment.objects.filter(path_id=OuterRef("path_id"))
+            ),
+        ).filter(
+            has_attachment=False,
+            has_archived_attachment=False,
+        )
+        # The majority of these rows will have attachment rows still,
+        # so we will only be deleting a small number of
+        # image_attachment rows per batch; the lookups for attachment
+        # and archived_attachment are both by unique path_id, so this
+        # query will still be fast.
+        batch_size = 10000
+        while min_id <= max_id:
+            lower = min_id
+            upper = min_id + batch_size
+            q.filter(id__gte=lower, id__lt=upper).delete()
+            min_id = upper
+            if min_id > max_id:
+                cursor.execute(SQL("SELECT MAX(id) FROM {}").format(Identifier(table)))
+                (max_id,) = cursor.fetchone()
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("zerver", "0771_alter_realmemoji_author"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            delete_unattached_imageattachments,
+            reverse_code=migrations.RunPython.noop,
+            elidable=True,
+        ),
+    ]