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+## Some useful SQL queries for Synapse Admins
+
+## Size of full matrix db
+`SELECT pg_size_pretty( pg_database_size( 'matrix' ) );`
+### Result example:
+```
+pg_size_pretty
+----------------
+ 6420 MB
+(1 row)
+```
+## Show top 20 larger rooms by state events count
+```sql
+SELECT r.name, s.room_id, s.current_state_events
+ FROM room_stats_current s
+ LEFT JOIN room_stats_state r USING (room_id)
+ ORDER BY current_state_events DESC
+ LIMIT 20;
+```
+
+and by state_group_events count:
+```sql
+SELECT rss.name, s.room_id, count(s.room_id) FROM state_groups_state s
+LEFT JOIN room_stats_state rss USING (room_id)
+GROUP BY s.room_id, rss.name
+ORDER BY count(s.room_id) DESC
+LIMIT 20;
+```
+plus same, but with join removed for performance reasons:
+```sql
+SELECT s.room_id, count(s.room_id) FROM state_groups_state s
+GROUP BY s.room_id
+ORDER BY count(s.room_id) DESC
+LIMIT 20;
+```
+
+## Show top 20 larger tables by row count
+```sql
+SELECT relname, n_live_tup as rows
+ FROM pg_stat_user_tables
+ ORDER BY n_live_tup DESC
+ LIMIT 20;
+```
+This query is quick, but may be very approximate, for exact number of rows use `SELECT COUNT(*) FROM <table_name>`.
+### 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 rooms by new events count in last 1 day:
+```sql
+SELECT e.room_id, r.name, COUNT(e.event_id) cnt FROM events e
+LEFT JOIN room_stats_state r USING (room_id)
+WHERE e.origin_server_ts >= DATE_PART('epoch', NOW() - INTERVAL '1 day') * 1000 GROUP BY e.room_id, r.name ORDER BY cnt DESC LIMIT 20;
+```
+
+## Show top 20 users on homeserver by sent events (messages) at last month:
+```sql
+SELECT user_id, SUM(total_events)
+ FROM user_stats_historical
+ WHERE TO_TIMESTAMP(end_ts/1000) AT TIME ZONE 'UTC' > date_trunc('day', now() - interval '1 month')
+ GROUP BY user_id
+ ORDER BY SUM(total_events) DESC
+ LIMIT 20;
+```
+
+## Show last 100 messages from needed user, with room names:
+```sql
+SELECT e.room_id, r.name, e.event_id, e.type, e.content, j.json FROM events e
+ LEFT JOIN event_json j USING (room_id)
+ LEFT JOIN room_stats_state r USING (room_id)
+ WHERE sender = '@LOGIN:example.com'
+ AND e.type = 'm.room.message'
+ ORDER BY stream_ordering DESC
+ LIMIT 100;
+```
+
+## Show top 20 larger tables by storage size
+```sql
+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
+```
+
+## Show rooms with names, sorted by events in this rooms
+`echo "select event_json.room_id,room_stats_state.name from event_json,room_stats_state where room_stats_state.room_id=event_json.room_id" | psql synapse | sort | uniq -c | sort -n`
+### Result example:
+```
+ 9459 !FPUfgzXYWTKgIrwKxW:matrix.org | This Week in Matrix
+ 9459 !FPUfgzXYWTKgIrwKxW:matrix.org | This Week in Matrix (TWIM)
+ 17799 !iDIOImbmXxwNngznsa:matrix.org | Linux in Russian
+ 18739 !GnEEPYXUhoaHbkFBNX:matrix.org | Riot Android
+ 23373 !QtykxKocfZaZOUrTwp:matrix.org | Matrix HQ
+ 39504 !gTQfWzbYncrtNrvEkB:matrix.org | ru.[matrix]
+ 43601 !iNmaIQExDMeqdITdHH:matrix.org | Riot
+ 43601 !iNmaIQExDMeqdITdHH:matrix.org | Riot Web/Desktop
+```
+
+## Lookup room state info by list of room_id
+```sql
+SELECT rss.room_id, rss.name, rss.canonical_alias, rss.topic, rss.encryption, rsc.joined_members, rsc.local_users_in_room, rss.join_rules
+FROM room_stats_state rss
+LEFT JOIN room_stats_current rsc USING (room_id)
+WHERE room_id IN (WHERE room_id IN (
+ '!OGEhHVWSdvArJzumhm:matrix.org',
+ '!YTvKGNlinIzlkMTVRl:matrix.org'
+)
+```
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