spc-pleroma/priv/repo/migrations/20171109091239_add_actor_to_activity.exs

defmodule Pleroma.Repo.Migrations.AddActorToActivity do
  use Ecto.Migration

  @disable_ddl_transaction true

  def up do
    alter table(:activities) do
      add :actor, :string
    end

    create index(:activities, [:actor, "id DESC NULLS LAST"], concurrently: true)
  end

  def down do
    drop_if_exists index(:activities, [:actor, "id DESC NULLS LAST"])
    alter table(:activities) do
      remove :actor
    end
  end
end