Use more efficient user note count update query.

priv/repo/migrations/20171024121413_add_object_actor_index.exs

@@ -0,0 +1,9 @@
+defmodule Pleroma.Repo.Migrations.AddObjectActorIndex do
+  use Ecto.Migration
+
+  @disable_ddl_transaction true
+
+  def change do
+    create index(:objects, ["(data->>'actor')", "(data->>'type')"], concurrently: true, name: :objects_actor_type)
+  end
+end