Pull request #23 has introduced a regression: the query against pg_stat_replication now joins with pg_replication_slots on pg_stat_replication.pid=pg_replication_slots.active_pid. But pg_replication_slots.active_pid is not a valid column, see https://www.postgresql.org/docs/9.4/static/catalog-pg-replication-slots.html. In light of that and the fact that pg_replication_slots is only present in 9.4 (not in 9.2, 9.5, etc) I suggest reverting this change altogether.