I would like editor access to the wiki, my username is amorris and I would like to modify https://wiki.postgresql.org/wiki/Lock_Monitoring
The existing query:
SELECT blocked_locks.pid AS blocked_pid, blocked_activity.usename AS blocked_user, blocking_locks.pid AS blocking_pid, blocking_activity.usename AS blocking_user, blocked_activity.query AS blocked_statement, blocking_activity.query AS current_statement_in_blocking_process FROM pg_catalog.pg_locks blocked_locks JOIN pg_catalog.pg_stat_activity blocked_activity ON blocked_activity.pid = blocked_locks.pid JOIN pg_catalog.pg_locks blocking_locks ON blocking_locks.locktype = blocked_locks.locktype AND blocking_locks.database IS NOT DISTINCT FROM blocked_locks.database AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid AND blocking_locks.pid != blocked_locks.pid JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid WHERE NOT blocked_locks.granted;
does not work for cases where there are multiple transactions, it starts reporting additional bloced/blocking pairs that don't exist!
I have the following query that works for simple and complex cases with multiple transactions blocked by the same transaction:
SELECT blocker.pid AS blocker_id, blocker.datname AS blocker_db, blocker.application_name AS blocker_app, blocker.xact_start AS blocker_tx_start, blocker.query AS blocker_cur_query, -- blocked.pid as blocked_pid, blocked.datname as blocked_db, blocked.application_name AS blocked_app, now() - blocked.query_start AS blocked_duration, blocked.query as blocked_query
FROM pg_stat_activity AS blocked
JOIN pg_stat_activity AS blocker ON blocker.pid = ANY(pg_blocking_pids(blocked.pid))
order by blocked_duration desc;