Some queries require the pg_stat_statement module to be installed.
        http://www.postgresql.org/docs/current/static/pgstatstatements.html

        :returns: boolean

def pg_stat_statement(self):
        """
        Some queries require the pg_stat_statement module to be installed.
        http://www.postgresql.org/docs/current/static/pgstatstatements.html

        :returns: boolean
        """

        if self._pg_stat_statement is None:
            results = self.execute(sql.PG_STAT_STATEMENT)
            is_available = results[0].available

            if is_available:
                self._pg_stat_statement = True
            else:
                self._pg_stat_statement = False

        return self._pg_stat_statement