drop_if_exists

Runner.ex

  defp execute_in_direction(repo, :forward, level, {:create_if_not_exists, %Index{}=index}) do
    if !repo.adapter.ddl_exists?(repo, index, @opts) do
      repo.adapter.execute_ddl(repo, {:create, index}, @opts)
    end
  end

  defp execute_in_direction(repo, :backward, level, {:drop_if_exists, %Index{}=index}) do
    if !repo.adapter.ddl_exists?(repo, index, @opts) do
      repo.adapter.execute_ddl(repo, {:create, index}, @opts)
    end
  end