pleroma/priv/repo/migrations/20230618190919_create_domains.exs

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

  def change do
    create_if_not_exists table(:domains) do
      add(:domain, :citext)
      add(:public, :boolean)

      timestamps()
    end

    create_if_not_exists(unique_index(:domains, [:domain]))

    alter table(:users) do
      add(:domain_id, references(:domains))
    end
  end
end