akkoma/priv/repo/migrations/20190123092341_users_add_is_admin_index.exs

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

  def change do
    create_if_not_exists(
      index(:users, ["(info->'is_admin')"], name: :users_is_admin_index, using: :gin)
    )
  end
end