Pleroma/priv/repo/migrations/20180606173637_create_apid_host_extraction_index.exs

defmodule Pleroma.Repo.Migrations.CreateApidHostExtractionIndex do
  use Ecto.Migration
  @disable_ddl_transaction true

  def change do
    create index(:activities, ["(split_part(actor, '/', 3))"], concurrently: true, name: :activities_hosts)
  end
end