ALTER TABLE public.invoices
  ADD COLUMN IF NOT EXISTS recurrence_frequency text,
  ADD COLUMN IF NOT EXISTS next_generation_date date,
  ADD COLUMN IF NOT EXISTS recurrence_end_date date,
  ADD COLUMN IF NOT EXISTS parent_invoice_id uuid REFERENCES public.invoices(id) ON DELETE SET NULL;

CREATE INDEX IF NOT EXISTS idx_invoices_recurrence_due
  ON public.invoices (next_generation_date)
  WHERE recurrence_frequency IS NOT NULL;