Finding blocked queries and their blockers in PostgreSQL

blockedQueries.sql

with blocked as (
    SELECT pid                               AS blocked_pid
         , usename                           AS blocked_username
         , query                             AS blocked_query
         , query_start                       AS blocked_start
         , wait_event                        AS blocked_wait_event
         , wait_event_type                   AS blocked_event_type
         , unnest( pg_blocking_pids( pid ) ) AS blocked_by
      FROM pg_stat_activity
     WHERE cardinality( pg_blocking_pids( pid ) ) > 0
    )
select blocked.*
     , blocking.usename
     , blocking.query
     , blocking.query_start
     , blocking.wait_event
     , blocking.wait_event_type
     , blocking.state
  from blocked
  join pg_stat_activity blocking on blocking.pid = blocked.blocked_by
order by query_start ;