Query pgbouncer for various metrics

def _collect_stats(self, db, instance_tags):
        """Query pgbouncer for various metrics
        """

        metric_scope = [self.STATS_METRICS, self.POOLS_METRICS, self.DATABASES_METRICS]

        try:
            with db.cursor(cursor_factory=pgextras.DictCursor) as cursor:
                for scope in metric_scope:
                    descriptors = scope['descriptors']
                    metrics = scope['metrics']
                    query = scope['query']

                    try:
                        self.log.debug("Running query: %s", query)
                        cursor.execute(query)

                        rows = cursor.fetchall()

                    except pg.Error:
                        self.log.exception("Not all metrics may be available")

                    else:
                        for row in rows:
                            self.log.debug("Processing row: %r", row)

                            # Skip the "pgbouncer" database
                            if row['database'] == self.DB_NAME:
                                continue

                            tags = list(instance_tags)
                            tags += ["%s:%s" % (tag, row[column]) for (column, tag) in descriptors if column in row]
                            for (column, (name, reporter)) in metrics:
                                if column in row:
                                    reporter(self, name, row[column], tags)

                        if not rows:
                            self.log.warning("No results were found for query: %s", query)

        except pg.Error:
            self.log.exception("Connection error")

            raise ShouldRestartException