Add index for user follower address.

priv/repo/migrations/20180325172351_add_follower_address_index_to_users.exs

@@ -0,0 +1,8 @@
+defmodule Pleroma.Repo.Migrations.AddFollowerAddressIndexToUsers do
+  use Ecto.Migration
+
+  @disable_ddl_transaction true
+  def change do
+    create index(:users, [:follower_address], concurrently: true)
+  end
+end