docs: def _create_index(self, table_name, index_columns):
          """
          Creates an index over multiple columns of a given table.
  
          Parameters
          ----------
          table_name : str
  
          index_columns : iterable of str
              Which columns should be indexed
          """
  
          logger.info(
              "Creating index on %s (%s)",
              table_name,
              ", ".join(index_columns))
          index_name = "%s_index_%s" % (
              table_name,
              "_".join(index_columns))
          self.connection.execute(
              "CREATE INDEX IF NOT EXISTS %s ON %s (%s)" % (
                  index_name,
                  table_name,
                  ", ".join(index_columns)))