First easy SQL queries for analyze database stats

SQL-queries-for-analyze-Matrix-Synapse-PosrgreSQL-database-stats.md

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+## Show top 20 larger rooms by state events count
+```
+SELECT r.name, s.room_id, s.state_events
+  FROM room_stats s
+  LEFT JOIN room_names r USING (room_id)
+  ORDER BY ts DESC, state_events DESC
+  LIMIT 20;
+```
+
+## Show top 20 larger tables by row count
+```
+SELECT relname, n_live_tup as rows
+  FROM pg_stat_user_tables 
+  ORDER BY n_live_tup DESC
+  LIMIT 20;
+```
+### Result example:
+```
+state_groups_state - 161687170
+event_auth - 8584785
+event_edges - 6995633
+event_json - 6585916
+event_reference_hashes - 6580990
+events - 6578879
+received_transactions - 5713989
+event_to_state_groups - 4873377
+stream_ordering_to_exterm - 4136285
+current_state_delta_stream - 3770972
+event_search - 3670521
+state_events - 2845082
+room_memberships - 2785854
+cache_invalidation_stream - 2448218
+state_groups - 1255467
+state_group_edges - 1229849
+current_state_events - 1222905
+users_in_public_rooms - 364059
+device_lists_stream - 326903
+user_directory_search - 316433
+```
+## Show top 20 larger tables by storage size
+```
+SELECT nspname || '.' || relname AS "relation",
+    pg_size_pretty(pg_total_relation_size(C.oid)) AS "total_size"
+  FROM pg_class C
+  LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
+  WHERE nspname NOT IN ('pg_catalog', 'information_schema')
+    AND C.relkind <> 'i'
+    AND nspname !~ '^pg_toast'
+  ORDER BY pg_total_relation_size(C.oid) DESC
+  LIMIT 20;
+```
+### Result example:
+```
+public.state_groups_state - 27 GB
+public.event_json - 9855 MB
+public.events - 3675 MB
+public.event_edges - 3404 MB
+public.received_transactions - 2745 MB
+public.event_reference_hashes - 1864 MB
+public.event_auth - 1775 MB
+public.stream_ordering_to_exterm - 1663 MB
+public.event_search - 1370 MB
+public.room_memberships - 1050 MB
+public.event_to_state_groups - 948 MB
+public.current_state_delta_stream - 711 MB
+public.state_events - 611 MB
+public.presence_stream - 530 MB
+public.current_state_events - 525 MB
+public.cache_invalidation_stream - 466 MB
+public.receipts_linearized - 279 MB
+public.state_groups - 160 MB
+public.device_lists_remote_cache - 124 MB
+public.state_group_edges - 122 MB
+```
+
+