Блокировки

Поиск заблокированных процессов

SELECT pid, 
       usename, 
       pg_blocking_pids(pid) as blocked_by, 
       query as blocked_query
  FROM pg_stat_activity
 WHERE cardinality(pg_blocking_pids(pid)) > 0;

Ссылки

https://stackoverflow.com/questions/26489244/how-to-detect-query-which-holds-the-lock-in-postgres