lock_blocking_waiting_pg_locks.sql

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_query,
    blocking_activity.query AS blocking_query,
    blocked_activity.query_start AS blocked_query_start,
    blocking_activity.query_start AS blocking_query_start
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;

-- Example results:
-- Using Rideshare as an example database, explicit LOCK on the "trips"
-- table within a transaction, then a SELECT * FROM trips that's blocked:


--  blocked_pid | blocked_user | blocking_pid | blocking_user |    blocked_query     | blocking_query |      blocked_query_start      |     blocking_query_start
-- -------------+--------------+--------------+---------------+----------------------+----------------+-------------------------------+-------------------------------
--        94003 | postgres     |        92606 | postgres      | select * from trips; | lock trips;    | 2024-07-10 15:13:18.758721-05 | 2024-07-10 15:12:56.844562-05
-- (1 row)
--