code: def rename_columns(cr, column_spec):
      
      for table in column_spec.keys():
          for (old, new) in column_spec[table]:
              if new is None:
                  new = get_legacy_name(old)
              logger.info("table %s, column %s: renaming to %s",
                          table, old, new)
              cr.execute(
                  'ALTER TABLE "%s" RENAME "%s" TO "%s"' % (table, old, new,))
              cr.execute('DROP INDEX IF EXISTS "%s_%s_index"' % (table, old))
docs: Rename table columns. Typically called in the pre script.
  
      :param column_spec: a hash with table keys, with lists of tuples as \
      values. Tuples consist of (old_name, new_name). Use None for new_name \
      to trigger a conversion of old_name using get_legacy_name()