diff --git a/sample-config/pgmon-metrics.yml b/sample-config/pgmon-metrics.yml
index 711e2a9..dcf6588 100644
--- a/sample-config/pgmon-metrics.yml
+++ b/sample-config/pgmon-metrics.yml
@@ -1,5 +1,7 @@
 metrics:
+  ##
   # Discovery metrics
+  ##
   discover_dbs:
     type: set
     query:
@@ -14,7 +16,9 @@ metrics:
       90400: SELECT slot_name, plugin, slot_type, database, false as temporary, active FROM pg_replication_slots
       100000: SELECT slot_name, plugin, slot_type, database, temporary, active FROM pg_replication_slots
 
+  ##
   # cluster-wide metrics
+  ##
   version:
     type: value
     query:
@@ -26,12 +30,20 @@ metrics:
       0: SELECT max(age(datfrozenxid)) AS xid_age, 0 AS mxid_age FROM pg_database
       90600: SELECT max(age(datfrozenxid)) AS xid_age, max(mxid_age(datminmxid)) AS mxid_age FROM pg_database
 
+  bgwriter:
+    type: row
+    query:
+      0: SELECT checkpoints_timed, checkpoints_req, checkpoint_write_time, checkpoint_sync_time, buffers_checkpoint, buffers_clean, maxwritten_clean, buffers_backend, buffers_backend_fsync, buffers_alloc FROM pg_stat_bgwriter;
+
+
+  ##
   # Per-database metrics
+  ##
   db_stats:
     type: row
     query:
-      0: SELECT numbackends, xact_commit, xact_rollback, blks_read, blks_hit, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted, conflicts, temp_files, temp_bytes, deadlocks, blk_read_time, blk_write_time, extract('epoch' from stats_reset)::float FROM pg_stat_database WHERE datname = %(dbname)s
-      140000: SELECT numbackends, xact_commit, xact_rollback, blks_read, blks_hit, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted, conflicts, temp_files, temp_bytes, deadlocks, COALESCE(checksum_failures, 0) AS checksum_failures, blk_read_time, blk_write_time, session_time, active_time, idle_in_transaction_time, sessions, sessions_abandoned, sessions_fatal, sessions_killed, extract('epoch' from stats_reset)::float FROM pg_stat_database WHERE datname = %(dbname)s
+      0: SELECT numbackends, xact_commit, xact_rollback, blks_read, blks_hit, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted, conflicts, temp_files, temp_bytes, deadlocks, 0 AS checksum_failures, blk_read_time, blk_write_time, 0 AS session_time, 0 AS active_time, 0 AS idle_in_transaction_time, 0 AS sessions, 0 AS sessions_abandoned, 0 AS sessions_fatal, 0 AS sessions_killed, extract('epoch' from stats_reset)::float AS stats_reset FROM pg_stat_database WHERE datname = %(dbname)s
+      140000: SELECT numbackends, xact_commit, xact_rollback, blks_read, blks_hit, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted, conflicts, temp_files, temp_bytes, deadlocks, COALESCE(checksum_failures, 0) AS checksum_failures, blk_read_time, blk_write_time, session_time, active_time, idle_in_transaction_time, sessions, sessions_abandoned, sessions_fatal, sessions_killed, extract('epoch' from stats_reset)::float AS stats_reset FROM pg_stat_database WHERE datname = %(dbname)s
     test_args:
       dbname: postgres
 
@@ -40,13 +52,21 @@ metrics:
     query:
       0: SELECT sum(heap_blks_read)::float / NULLIF(sum(heap_blks_read + heap_blks_hit), 0) AS avg_heap_hit_ratio, sum(idx_blks_hit)::float / NULLIF(sum(idx_blks_read + idx_blks_hit), 0) AS avg_idx_hit_ratio, sum(toast_blks_hit)::float / NULLIF(sum(toast_blks_read + toast_blks_hit), 0) AS avg_toast_hit_ratio, sum(tidx_blks_hit)::float / NULLIF(sum(tidx_blks_read + tidx_blks_hit), 0) AS avg_tidx_hit_ratio FROM pg_statio_all_tables
 
-  # Debugging
-  ntables:
-    type: value
+  activity:
+    type: row
     query:
-      0: SELECT count(*) AS ntables FROM pg_stat_user_tables
+      0: >
+        SELECT count(*) as backend_count,
+               count(*) FILTER (WHERE state = 'idle') AS idle_count,
+               count(*) FILTER (WHERE state = 'idle in transaction') AS idle_tx_count,
+               COALESCE(EXTRACT(EPOCH FROM max(now() - state_change) FILTER (WHERE state = 'active'))::float, 0) AS max_active_time,
+               COALESCE(EXTRACT(EPOCH FROM max(now() - state_change) FILTER (WHERE state = 'idle in transaction'))::float, 0) AS max_idle_tx_time
+        FROM pg_stat_activity
+        WHERE datname = %(dbname)s
 
+  ##
   # Per-replication metrics
+  ##
   rep_stats:
     type: row
     query:
@@ -54,7 +74,10 @@ metrics:
     test_args:
       repid: 127.0.0.1_test_rep
 
+
+  ##
   # Per-slot metrics
+  ##
   slot_stats:
     type: row
     query:
@@ -62,3 +85,11 @@ metrics:
       100000: SELECT active_pid, xmin, pg_wal_lsn_diff(pg_current_wal_lsn(), restart_lsn) AS restart_bytes, pg_wal_lsn_diff(pg_current_wal_lsn(), confirmed_flush_lsn) AS confirmed_flush_bytes FROM pg_replication_slots WHERE slot_name = %(slot)s
     test_args:
       slot: test_slot
+
+  ##
+  # Debugging
+  ##
+  ntables:
+    type: value
+    query:
+      0: SELECT count(*) AS ntables FROM pg_stat_user_tables